UPDATED Dec. 14 at 1 p.m.
MSNBC -- Twenty-seven people were killed, including 20 children, when a gunman opened fire in a Connecticut elementary school Friday morning, a law enforcement official said.
The gunman, who is dead, was Adam Lanza, a 20-year-old from Connecticut, an official said. He was wearing all black and was carrying two 9mm handguns and .223-caliber assault rifle. Lanza's mother worked at the school and was shot dead on scene in her kindergarten class. Another family member is dead at their Newtown, Conn. home.
"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 at Sandy Hook Elementary School in Newtown told NBC Connecticut during its live broadcast. "And I kept hearing these booming noises. And we all … started crying.
"All the gym teachers told us to go into the office where no one could find us," she added. "So then a police officer came in and told us to run outside. So we did and we came in the firehouse and waited for our parents."
Two 9mm handguns were recovered from the scene, an official told WNBC's Jonathan Dienst.
Three people were taken to nearby Danbury Hospital, a spokeswoman told NBC Connecticut. She would not elaborate on the ages of the victims or their conditions.
One of those taken to the hospital was a teacher who had been shot in the foot, the Associated Press reported, citing a dispatcher at the Newtown Volunteer Ambulance Corps.
The Newtown Bee  reported that one child, apparently wounded, was carried from the scene by a police officer.
A third-grader, Alexis Wasik, told the Hartford Courant  that police checked students and staffers before they were escorted to the fire station.
"We had to walk with a partner," she said.
NBC Connecticut  reported that the entire school district was in lockdown.
At Sandy Hook, police, ATF and FBI agents were going room to room searching the school.
President Obama was notified about the shooting and continues to receive updates, according to a White House official.
Newtown is about 45 miles southwest of Hartford and 60 miles northeast of New York City.
The K-4 school has about 600 students.