A law enforcement official says all those killed at a Texas elementary school were in the same fourth-grade classroom

BREAKING: A law enforcement official says all those killed at a Texas elementary school were in the same fourth-grade classroom. Nineteen children and two teachers were killed in the shooting.

(AP) — The 18-year-old gunman who slaughtered 19 children and two teachers at a Texas elementary school barricaded himself inside a single classroom and “began shooting anyone that was in his way,” authorities said Wednesday in detailing the latest mass killing to rock the U.S.

Law enforcement officers eventually broke into the classroom and killed the gunman, who used an AR-style rifle. Police and others responding to Tuesday’s attack also went around breaking windows at the school to enable students and teachers to escape, Lt. Christopher Olivarez of the Texas Department of Public Safety said on NBC’s “Today” show.

Olivarez told CNN that all the victims were in the same fourth-grade classroom at Robb Elementary.

The killer “barricaded himself by locking the door and just started shooting children and teachers that were inside that classroom,” he said. “It just shows you the complete evil of the shooter.”

Dillon Silva, whose nephew was in a nearby classroom, said students were watching a movie when a bullet shattered a window. Moments later, their teacher saw the armed assailant walk past the door.

“Oh, my God, he has a gun!” the teacher shouted twice, according to Silva. “The teacher didn’t even have time to lock the door,” he said.