SEFFNER 
 
 Jeremy Bush just went to bed when he heard what sounded like a car hitting the house. Then screams from his brother Jeffrey's bedroom. 
 
 "Help me! Help me!" 
 
 Someone flipped the lights. Jeremy, 36, threw the door open, revealing a sight that defied belief: The earth had opened beneath his brother's bedroom and was swallowing everything in it. The tip of Jeffrey's mattress was the only thing left, and it was sinking into a churning sinkhole. 
 
 Someone in the house called 911: "The bedroom floor collapsed and my brother-in-law is underneath the house." 
 
 Hillsborough County sheriff's Deputy Douglas Duvall was not sure exactly what that meant until he got to the one-story house at 240 Faithway Drive just after 11 p.m. Thursday and found Jeremy Bush trying in vain to dig into a hole threatening to claim him. Duvall pulled him to safety. 
 
 Then the waiting began. 
 
 An army of rescue authorities came, followed by an army of media, and everyone tiptoed around yellow caution tape and bulging television station cables Friday as the rescuers tried to figure out what they could do, safely, to find a man buried in an expanding sinkhole. 
 
 In the midst of the scrum sat the friends and family of 37-year-old road worker Jeffrey S. Bush, sobbing, consoling each other, screaming at rescue workers, struggling to come to terms with the fact the rubble under the aqua home Bush lived in may be his final resting place. 
 
 No officials declared Bush dead, but rescue efforts were hampered by the volatile nature of sinkholes. Authorities did not give the family false hope. Still, some had it. 
 
 "Until I see him, until they get him out," Amber Wicker, Jeffrey's friend, said midday, "you have to hold on." 
 
 • • • 
 
 The noise that startled the residents of the Seffner home, experts say, was a cover collapse sinkhole — the rarest kind and, because of its suddenness, often the most catastrophic. 
 
 Cover collapse sinkholes usually occur in areas where a layer of clay sits atop the Swiss cheese of limestone that lies beneath the ground in this part of the state, said University of South Florida geology professor Mark Stewart. 
 
 The limestone is pocked with caverns. Something triggers the clay atop a cavern to begin trickling into the hole, more and more of it drops away until all that's left is a slender land bridge. Then the bridge falls. 
 
 The bang is the last bit of sediment falling into the bottom of the cavern, Stewart said. 
 
 The sinkhole that took Jeffrey Bush was 30 feet wide and 20 feet deep, Hillsborough County Fire Rescue Chief Ron Rogers estimated. It was confined to the home, not visible from the outside. 
 
 Sinkholes can occur naturally. They can also be caused by humans building homes, stores or retention ponds atop fragile land, or pumping too much water out of the aquifer. 
 
 In a record cold snap in 2010, Plant City strawberry farmers pumped about 1 billion gallons of water from the aquifer to protect their crops. The aquifer dropped some 60 feet, causing multiple sinkholes in the area. 
 
 Stewart was skeptical that over-pumping caused this sinkhole. Sandy Nettles, a private geologist in Palm Harbor, said recent rainfall may have played a role. 
 
 January and February were both drier than normal. That can cause the aquifer to dip, weakening underground support for the land above a cavern, Nettles said. A recent downpour could have washed away what little remained of the cap atop the cavern. 
 
 "Obviously that cavern was ready to go," Nettles said. "It doesn't take much of a fluctuation in the water table to make it slip." 
 
 In the early 1980s, state officials were determined to solve the mysteries behind the cause of sinkholes. In 1981, during a drought, a gigantic sinkhole opened in Winter Park, swallowing a car dealership, a home and part of a road. The Legislature created a research institute at the University of Central Florida. 
 
 After a while, according to Stewart, legislators cut funding. 
 
 "They figured, 'We don't need this any more,' " he said. "We haven't had another one of these in the news in a while." 
 
 • • • 
 
 The Bush brothers both worked for the Florida Department of Transportation, Jeremy said, doing roadside assistance. His brother moved to the home three months ago from Zephyrhills. They lived there with Jeremy's fiancee, Rachel Wicker, their 2-year-old daughter, Hanna, and two other relatives. 
 
 Leland Wicker, owner of the home, was vacationing in North Carolina on Thursday night. He said the four-bedroom home, built in 1974, passed a sinkhole inspection in August and is insured. 
 
 The friends and family of Jeffrey Bush gathered near the house Friday morning and, adhering to the cordoned off safety zone, dragged lawn chairs in front of the homes across the street. Many of them still wore pajamas. They walked in circles, their eyes glazed, rimmed in red, their hands trembling, gripping cigarettes. Some talked about charging past the workers and digging Bush out themselves. Some didn't talk, just clinging to stuffed animals and staring across the street. 
 
 And they watched. 
 
 About noon, they watched a team send an underground camera into the stormwater pipes. About 2:30 p.m., they watched workers roll drilling equipment out front of the home. At 3, they watched the equipment stop working and then watched a man crawl underneath the equipment with a wrench and work for more than 30 minutes. 
 
 Just after 4 p.m., a sheriff's deputy asked them to move back, for their safety. Emotions boiled over. 
 
 Jeremy Bush cursed and looked across the street at the workers in the yard. 
 
 He stormed off down the street, threatening to punch firefighters. An older woman ran after him, and they met in an embrace in the middle of the street, both crying. Then Jeremy walked off, and the woman went back to her lawn chair, sobbing. 
 
 "My baby's in a hole," she said. 
 
 About 6:30 p.m., a line of county officials held a news conference to say they were doing all that they could. 
 
 "Until we know where it's safe to bring our equipment," Chief Rogers said, "we're really handicapped." 
 
 Then Deputy Duvall, the first on scene, spoke. 
 
 Duvall's shift ended at 7 a.m. He tried to sleep, but couldn't. He came back because he wanted to be here. This neighborhood had warmed his heart with how it helped the family, he said. 
 
 "These are everyday, working people. They're good people." 
 
 Then he looked at the cameras. He had a message for viewers. 
 
 "You guys out there, if you know these people, if you know this neighborhood, pray for them." 
 
 Times photographer Luis Santana and staff writers Craig Pittman and Stephanie Bolling contributed to this report. ||||| Story highlights Man's brother talks to CNN's "AC360" about trying to save his brother 
 
 Site remains unstable, complicating recovery efforts 
 
 "It's a tough situation. It's even tougher for the family," says a fire chief 
 
 Authorities release the audio of a 911 call: "The house just fell through" 
 
 The ground just swallowed him up. 
 
 A Florida man fell into a sinkhole that opened suddenly Thursday night beneath the bedroom of his suburban Tampa home, calling out to his brother for help as he fell, the brother said Friday. 
 
 "I ran toward my brother's bedroom because I heard my brother scream," Jeremy Bush told CNN's "AC360." 
 
 "Everything was gone. My brother's bed, my brother's dresser, my brother's TV. My brother was gone." 
 
 Bush frantically tried to rescue his brother, Jeff Bush, by standing in the hole and digging at the rubble with a shovel until police arrived and pulled him out, saying the floor was still collapsing. 
 
 "I couldn't get him out. I tried so hard. I tried everything I could," he said through tears. "I could swear I heard him calling out." 
 
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 Jeremy Bush and four other people, including a 2-year-old child, escaped from the blue, one-story 1970s-era home in Seffner, a Tampa suburb. 
 
 Sinkholes: Common, costly and sometimes deadly 
 
 What began with hopes of rescue turned into a body recovery operation after monitoring equipment failed to detect any signs that Jeff Bush survived the fall into the hole, according the Hillsborough County Sheriff's Office. 
 
 Rescuers still hadn't gone into the hole -- it's too dangerous, Fire Chief Ron Rogers told reporters. Authorities say they worry the hole is still spreading and the house could collapse at any time. 
 
 "Until we know where it's safe to bring the equipment, we really are just handicapped and paralyzed, and can't really do a whole lot more than sit and wait. It's a tough situation. It's even tougher for the family," Rogers said. 
 
 The sinkhole is about 20 feet to 30 feet across and may be 30 feet deep, said Bill Bracken, president of an engineering company assisting emergency workers. The hole was originally reported to be 100 feet across, but that is the diameter of the safety zone surrounding it, Bracken said. 
 
 "It started in the bedroom, and it has been expanding outward and it's taking the house with it as it opens up," he said. 
 
 As the sinkhole continued to deepen, nearby homes were evacuated as a precaution. 
 
 Check out images of the sinkhole house 
 
 On Friday, the Hillsborough County Sheriff's Office released a 911 call from the night before. 
 
 "The house just fell through," a female voice says on the recording. She asks for an ambulance and the police. 
 
 "The bedroom floor just collapsed, and my brother-in-law is in there. He's underneath the house," she says. 
 
 Jessica Damico, Hillsborough County Fire Department spokeswoman, said about 40 police and firefighters were standing by at the scene Friday morning. Meanwhile, engineers hoped to use more sophisticated equipment to get a three-dimensional image of the sinkhole. 
 
 Family members were also on hand, waiting out what they feared would be a devastating day. 
 
 "I'm praying that there's an air pocket in there ... but I can't see nobody surviving that long in a hole like that. There was too much dirt, too much stuff," Jeremy Bush said. "He was my brother, man, I loved him." 
 
 Sinkholes are common in Florida, according to the Florida Department of Environmental Protection. The state lies on bedrock made of limestone or other carbonate rock that can be eaten away by acidic groundwater, forming voids that collapse when the rock can no longer support the weight of what's above it. 
 
 Hillsborough County is part of an area known as "sinkhole alley" that accounts for two-thirds of the sinkhole-related insurance claims in the state, according to a Florida state Senate Insurance and Banking Committee report. 
 
 But Mike Merrill, county administrator for Hillsborough County, stressed Friday that the sinkhole in question was not "your typical sinkhole." 
 
 "They still have not been able to find the boundaries of the underground chasm. For that reason, we're being very deliberate, he said. "We're very frustrated. But we're pursuing it as quickly as we can, as safely as we can."
– Engineers are still gingerly trying to find a 37-year-old Florida man who disappeared into a sinkhole that opened up in his bedroom yesterday. Jeffrey Bush is presumed dead, and authorities say the sinkhole is so dangerous they can't risk simply sending searchers into it, reports AP. It's about 30 feet wide and 20 feet deep, but it's growing slowly and expected to collapse even more. "This is not your typical sinkhole," says one Tampa-area official. "This is a chasm. For that reason, we're being very deliberate." Bush's family is livid, especially his brother, Jeremy, who tried in vain to pull his brother out when the sinkhole suddenly appeared Thursday night. He had to be rescued himself by a firefighter. "I could swear I heard him hollering my name to help him," Jeremy tells the Tampa Bay Times. The newspaper says this is a "cover collapse sinkhole," the rarest and most dangerous kind because there's no warning. "You can almost envision a piece of Swiss cheese," explains one geologist, referring to the region's porous limestone.