Sixteen people are dead after a large hot air balloon struck a high-voltage power line, caught fire and crashed in a pasture near Lockhart, Texas, this morning, according to Texas authorities and the Federal Aviation Administration. 
 
 The Caldwell County Sheriff's Office received a 911 call around 7:44 a.m. local time about a possible vehicle accident. The fire apparently broke out during flight in the basket portion of the hot air balloon. 
 
 Witnesses described hearing popping sounds and then seeing a blaze of flames. 
 
 "The popping sound was the balloon connecting with the electric lines and then by the time I turned and saw the fireball go up, the basket was on the ground," witness Margaret Wylie said. 
 
 "All you could tell it was a fire, a big ball of flames and you could tell nothing what it was or anything," witness Don Schulle said. 
 
 The Sheriff's Office said that investigators are still determining the number and the identities of victims. 
 
 ESRI/AP 
 
 The FAA said its investigators are on their way to the crash scene and the National Transportation Safety Board, which will be in charge of the investigation, has been notified. 
 
 A full team of 13 NTSB are expected to arrive at the scene on Sunday. 
 
 NTSB Go-Team to Texas balloon accident delayed by weather in DC. Expected to arrive Sunday mid-morning. Expect briefing later in day. — NTSB_Newsroom (@NTSB_Newsroom) July 31, 2016 
 
 "The FAA and NTSB do not release the names of pilots or passengers. Names will be released by local officials after relatives have been notified," FAA spokesperson Lynn Lunsford said in a statement. 
 
 The balloon was operated by the Heart of Texas Hot Air Balloon Rides. The company is owned by Skip Nichols, who regularly celebrated his love of flying, posting photos and videos on his Facebook page. There were tributes posted on his page tonight, remembering a "great pilot" and a man who had a "happy go lucky outlook on life." 
 
 Today's hot air balloon crash was the deadliest in U.S. history since NTSB records began in 1964. 
 
 Texas Gov. Greg Abbott and his wife expressed their sympathy in a statement, saying "[We] extend our deepest condolences for all those who have been affected by today’s heartbreaking tragedy. Our thoughts and prayers are with the victims and their families, as well as the Lockhart community." 
 
 My statement on the tragic and heartbreaking event in Lockhart today https://t.co/MzkKodw9vW pic.twitter.com/28PTBr7tZe — Gov. Greg Abbott (@GovAbbott) July 30, 2016 
 
 ABC News' Jeff Cook, Marilyn Heck and Josh Margolin contributed to this report. ||||| (CNN) A hot air balloon believed to be carrying 16 people caught fire in the air and crashed in central Texas on Saturday morning, killing everybody on board, federal and local authorities said. 
 
 The balloon may have struck power lines when it went down around 7:30 a.m. in pastureland near Lockhart, about 30 miles south of Austin, in an area often used for balloon landings, a county judge and public safety source told CNN. 
 
 "First I heard a whoosh," Margaret Wylie, who lives near the crash site, told CNN affiliate TWC. "And then a big ball of fire (went) up. I'd say it got as high up as those lower electric lines." 
 
 If investigators confirm 16 people died, the crash will be the most fatal hot air balloon accident in United States history. 
 
 The hot air balloon rests on the ground near Lockhart, Texas. 
 
 Federal Aviation Authority officials said the balloon carrying 16 people caught fire before crashing, but provided few other details. The Caldwell County Sheriff's Office said nobody on board survived. 
 
 Caldwell County Judge Ken Schawe said it looks like the balloon collided with a power line before catching fire and crashing to the ground. 
 
 A source with the Texas Department of Public Safety earlier told CNN's Polo Sandoval that investigators believe the hot air balloon struck power lines and caught fire. This is the preliminary working theory, the source said. 
 
 CNN Map 
 
 Reported as a vehicle crash 
 
 Law enforcement officers responded to a 911 call at 7:44 a.m. (8:44 a.m. ET) about a possible auto accident in the Maxwell area, according to a statement on the Caldwell County Office of Emergency Management's Facebook page . Officers found the balloon basket on fire on the ground, the statement said. 
 
 The FAA and National Transportation Safety Board are investigating. 
 
 The NTSB says it is working with the FBI to document the crash site, which was secured like a crime scene for evidence collection. Authorities have not named any of the people on board. 
 
 The name of the company involved in the crash is Heart of Texas Hot Air Balloon Rides, an official with direct knowledge of the investigation told CNN's Rene Marsh. CNN was unable to reach anyone at the company for comment. 
 
 Balloon flights originate in several locations in central Texas and go to dozens of destinations at $399 per passenger, the company says on its website. 
 
 NTSB spokesman Christopher O'Neill said 16 was the maximum number of passengers allowed under federal regulations governing hot air balloon operations. 
 
 'A safe, competent pilot' 
 
 Texas DPS Trooper Robbie Barrera, center right, puts her arm around Caldwell County Sheriff Daniel Law as he arrives on the scene of a hot air balloon crash Saturday. 
 
 Philip Bryant, a balloon pilot, told CNN he knew the pilot of the balloon that crashed. 
 
 "I knew him to be a safe, competent pilot," Bryant said. "He has done this for a very long time." 
 
 Bryant said he'd also been told the balloon hit power lines. 
 
 "I don't know what would distract a pilot from seeing what was in front of him, but in this case that's apparently what happened," he said. 
 
 O'Neill provided a timetable for part of the investigation. 
 
 Several days will be spent on field work -- interviewing people and gathering evidence at the scene. Seven to 10 days after field work ends, the agency will issue a preliminary report "that's basically a snapshot of what facts do we know at that point in time." The preliminary report will not include a probable cause of the crash, he said. 
 
 Egyptian balloon crash killed 19 
 
 Gov. Greg Abbott and U.S. Sen. Ted Cruz of Texas extended condolences to the families of the people killed in the crash. 
 
 May God's restorative strength & grace be with the families affected by the tragic hot air balloon crash. #txlege https://t.co/1d2oPDVtj8 — Greg Abbott (@GregAbbott_TX) July 30, 2016 
 
 "As always, Texans are strong in the face of adversity, and we all stand together in support of the families and entire Lockhart community as they respond to and begin to heal from this terrible incident," Cruz said in a statement. 
 
 The highest number of deaths in a single hot air balloon crash in the country before Saturday was six, in a 1993 accident in Colorado, according to the NTSB. 
 
 In 2013, 19 people died in a hot air balloon crash in Egypt , near the ancient city of Luxor. That was the world's most fatal hot air balloon accident in at least 20 years. 
 
 NTSB sought more balloon oversight 
 
 There's been friction between the FAA and NTSB over hot air balloons, with the NTSB saying more accidents would occur without more regulation. 
 
 The former head of the NTSB, Chairman Deborah Hersman, urged the FAA in 2014 to address "operational deficiencies" in hot air balloon activities after several incidents resulted in injuries and one death, according to a letter published on the NTSB's website. 
 
 Hersman cited accidents in 2007, 2008 and 2013, according to the letter publicly posted on the federal agency's site. 
 
 "Depending on gondola capacity, balloons can carry more than 20 passengers per flight. Given the various safety deficiencies noted in the NTSB's investigations of the above balloon accidents, the potential for a high number of fatalities in a single air tour balloon accident is of particular concern if air tour balloon operators continue to conduct operations under less stringent regulations and oversight," Hersman said in the letter, referring to the 2013 accident in Egypt. 
 
 hot air balloon crash texas dombroff beeper_00014330.jpg 
 
 In the letter, Hersman recommended requiring commercial balloon operators to acquire and maintain letters of authorization to hold air tour flights and to give passengers "a similar level of safety oversight as passengers of air tour airplane and helicopter operations." 
 
 In 2015, the FAA responded to the NTSB request, saying the proposed letters of authorization "would not result in a significantly higher level of operational safety." 
 
 The NTSB argued the letters of authorization would allow for competency checks including pilot certification, safety checklists, and proper flight operation procedures. 
 
 "We are concerned that, if no action is taken to address this safety issue, we will continue to see such accidents in the future," the NTSB response said. 
 
 It is unclear whether Heart of Texas Hot Air Balloon Rides implemented any of the NTSB's recommended measures. 
 
 This 2004 file photo show large capacity hot air basket carrying tourist on safari in Masai Mara, Kenya. 
 
 Twenty-five balloon accidents resulting in 4 fatalities and 25 serious injuries occurred since Hersman's 2014 letter and the last warning issued by the NTSB in March 2016, according to the exchange posted on its website. 
 
 The number does not take into account the fatalities from Saturday's hot air balloon accident near Lockhart, Texas. ||||| LOCKHART, Texas (AP) — The Latest on the hot air balloon that crashed in Central Texas (all times local): 
 
 12:10 p.m. 
 
 The site of a hot air balloon crash in Central Texas appears to be directly under large power lines. 
 
 Authorities have said there are likely no survivors after a hot air balloon carrying at least 16 people caught fire and crashed near Lockhart on Saturday morning. 
 
 The land near the crash site is mostly farmland, with corn crops and grazing cattle. 
 
 Cutting through that farmland is a row of massive, high-capacity transmission lines, and the site of the crash appears to be right below the overhead lines. 
 
 Authorities are investigating the crash, and have not yet provided further details. A large number of law enforcement personnel is at the scene. 
 
 ___ 
 
 12 p.m. 
 
 Texas Gov. Greg Abbott says in a statement that he and the first lady are extending their condolences following a hot air balloon crash in which authorities say there are likely no survivors. 
 
 Abbott said in a statement Saturday that he and his wife, Cecilia Abbott, "extend our deepest condolences" for those affected" by the "heartbreaking tragedy." 
 
 Authorities have said there are likely no survivors after a hot air balloon carrying at least 16 people caught fire and crashed near Lockhart on Saturday morning. 
 
 Abbott says he and his wife's thoughts and prayers are with the victims and their families, as well as the Lockhart community. He says, "The investigation into the cause of this tragic accident will continue, and I ask all of Texas to join us in praying for those lost." 
 
 ___ 
 
 11:05 a.m. 
 
 Authorities say it is likely there are no survivors after a hot air balloon carrying at least 16 people caught on fire and crashed in Central Texas. 
 
 The Caldwell County Sheriff's Office said in a statement Saturday that investigators are determining the number of victims and their identities. 
 
 Lynn Lunsford with the Federal Aviation Administration said in an earlier statement that the accident happened shortly after 7:40 a.m. Saturday near Lockhart, Texas, when the hot air balloon crashed into a pasture. Lunsford said there were at least 16 people on board. 
 
 Lunsford said that the FAA and the National Transportation Safety Board are going to the scene to investigate. 
 
 Lockhart is about 30 miles south of Austin.
– A hot air balloon has crashed in Texas, killing all 16 people aboard, NBC News reports. According to the ABC News, a fire started in the basket of the hot air balloon before the balloon crashed into a pasture near Lockhart, Texas, on Saturday morning. The site of the crash appears to be underneath large, high-capacity power lines, the AP reports. Their possible role in the incident is unclear. Officials are continuing to investigate the crash.