Four people, including three children, have been killed in a shooting at a primary school in the US state of Oregon.
The attack in the city of Bend was carried out by a 16-year-old boy, police said. An armed bystander pursued the assailant into the school and shot him dead, officials added.
The children killed were aged five, eight and 11. A teacher was also killed. Another teacher and a seven-year-old pupil were taken to hospital with critical injuries, Bend Police Chief Mike Krantz said at a media conference.
The attacker entered the school by shooting through locked doors, police said, without offering any further details.
Oregon Governor Tina Kotek hailed the armed bystander who "heroically intervened to stop further loss of life" at Silver Rail Elementary School.
"No parent should have to have this kind of day, and no community should have to live through this kind of day," Ms Kotek said. "As we learn more about the children and the adults who have been killed or injured, and their families and their loved ones, we are going to do a lot of crying, and we are going to cry together, and we're probably going to cry privately."
Bend, in rural central Oregon, is home to about 100,000 people and is about 280km south-east of Portland.
Silver Rail Elementary School offers classes from kindergarten through to fifth grade – about ages five to 11 – and has about 450 pupils and 40 staff members, officials said.
Police said they received a call at about 1pm that indicated a man had shot into a car at Silver Rail Elementary School.
Moments later, emergency dispatchers received calls "reporting that a person had entered the school and began shooting", police said in a statement.
Officers arrived within three minutes and found that the suspect had been shot dead.