Elementary school massacre: 26 dead, including 18 kids, in Connecticut By Miguel Llanos and Tracy Connor, NBC News Updated at 1:30 p.m. ET: A young man clad in black and carrying two handguns shot up an elementary school in a small Connecticut town on Friday, leaving 18 small children and eight adults dead in one the nation's worst school massacres, law enforcement officials said. The gunman, described as a 20-year-old man from Connecticut, was later found dead, a federal law enforcement official told NBC News. A second person was in custody for a possible connection to the shooting, NBC's Pete William reported. Students - mostly under age 10 -- described the terror that gripped Sandy Hook Elementary School in Newtown when the rampage began around 9:30 a.m., sparking a massive police response that included SWAT officers going room to room to search for victims. The Hartford Courant, citing unnamed sources, said many of the victims were in a kindergarten classroom. "I was in the gym and I heard a loud, like seven loud booms, and the gym teachers told us to go in the corner, so we all huddled," one student told NBC Connecticut. Dozens of emergency vehicles from across Fairfield County raced to the 600-student school, along with panicked parents hoping to be reunited with their children. "It was horrendous," Brenda Lebinski, mother of a third-grader, said at the scene.``Everyone was in hysterics -- parents, students. There were kids coming out of the school bloodied. I don't know if they were shot, but they were bloodied," she said, according to Reuters. One parent picking up his young son said the shooting was "the most terrifying moment a parent can imagine." He described the anguish of waiting to find out if his son was a victim and then running to his child. "It was the greatest relief in my existence," the father said. I'm just happy that my kid's OK. Bracing for a large influx of wounded, Danbury Hospital went on lockdown and cleared four trauma rooms. It received only three patients, including a teacher shot in the foot, the Associated Press reported. The motive for the shooting was unknown, and the gunman's name was not released. The Associated Press said one of the guns was a.223-caliber rifle. The FBI was on the scene, assisting with the investigation. President Obama was told of the shooting at 10:30 a.m. "I think it's important on a day like today to view this as I know the president, as a father does, and I as a father and others who are parents certainly do, which is to feel enormous sympathy for families that are affected," White House press secretary Jay Carney said. The death toll is the highest from a school shooting in U.S. history since a gunman killed 32 people at Virginia Tech in 2007. At Columbine High School in Littleton, Colorado, two teens killed 13 people and wounded 24 in 1999. Parent Stephen Delgiadice, whose 8-year-old daughter was not hurt, said he never could have imagined such carnage in the small bedroom community - where the police force has only three detectives. "It's alarming, especially in Newtown, Connecticut, which we always thought was the safest place in America," he told The Associated Press. NBC's Pete Williams and WNBC's Jonathan Dienst contributed to this report. LIVE VIDEO - Connecticut state police hold a news conference in Newtown to comment on the investigation of a shooting at an elementary school.