Texas elementary school shooting: What do we know so far?

An official says an 18-year-old gunman who killed 19 children and two teachers at a Texas elementary school barricaded himself inside a classroom, ``shooting anyone that was in his way.''

Lt. Christopher Olivarez of the Texas Department of Public Safety told NBC's ``Today'' that police and others responding to Tuesday's attack broke windows at the school in an effort to allow students and teachers inside to escape.

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

Eventually law enforcement officers broke into the classroom and killed him.

A gunman stormed into Robb Elementary Tuesday and killed 19 children and two teachers.

It was the United States' deadliest school shooting in nearly a decade.

Investigators haven't disclosed any motives for the shootings.

Authorities haven't yet released the names of the dead, but some information about them has emerged from families of victims as young as 8.