A 16-year-old killed four at a Bend elementary school.

BEND, Ore. — A 16-year-old boy shot his way through the locked doors of Silver Rail Elementary School on Thursday and killed a teacher and three children, the Associated Press and The New York Times reported. The children were 5, 8 and 11. A 7-year-old and a 54-year-old teacher were taken to a hospital in critical condition. Police have not named the victims or the shooter. They said he was from Bend, and that it was not clear whether he knew anyone at the school.

The New York Times reported that he entered with a long gun, and that an armed bystander who followed him inside shot and killed him. The first 911 call came at 12:59 p.m. Pacific from a person in a car who said they had been shot at. The Associated Press said the shooting was the 28th mass killing in the United States this year, in the database it keeps with USA Today and Northeastern University. The school teaches kindergarten through fifth grade. About 400 students are enrolled.

A teacher and three children were killed. Police have not named them.

The photograph shows an officer holding the tape outside Silver Rail Elementary on Thursday. It is the school after the shooting. It is not the children, and it is not the shooter. The States desk does not name a boy the police have not named.