A 16-year-old has shot dead three children and a teacher at a primary school in the US state of Oregon before he was killed by a bystander, police said.
The suspect, who has not been named, forced his way into Silver Rail Elementary School in the city of Bend on Thursday afternoon by shooting at locked doors, Bend Police Chief Mike Krantz confirmed.
The teenager was shot dead by a community member who "pursued him into the school and engaged him", Krantz said. Police arrived three minutes later.
The three children killed were aged five, eight and 11. A seven-year-old and a 54-year-old teacher were taken to a hospital in a critical condition. It is unclear if the attacker had any links to the school.
"We are stunned and heartbroken by this senseless tragedy," Steven Cook, the top administrative official of the local school district, said in a statement.
"No words can adequately express the grief our community is experiencing."
Police said the attacker was a local 16-year-old boy, but they did not release any further details on him or the identity of the victims.
Police were alerted to an active shooter at Silver Rail Elementary at 12:59 local time (19:59 GMT), Bend Police Department spokeswoman Sheila Miller told reporters.
The first call came from a person who said that an unknown suspect was shooting into their car with a long gun, police said. Photos released from the scene show a red truck with bullet holes.
Minutes later, the local county dispatch received 911 calls reporting that the attacker had entered the school.
Police said he shot at locks on the doors in order to force his way inside.
Local media reports suggested the school received new classroom doors in 2022 which can be locked with the flip of a switch.
A bystander saw the shooting begin to unfold, pursued the attacker into the school and shot him dead, police explained.
Three minutes later, officers first arrived at the scene. They confirmed that the attacker had been killed, and then searched the school.
Oregon Governor Tina Kotek praised the bystander who "heroically intervened" to stop further loss of life.
"Your actions carry a heavy emotional burden and I just want you to know that my thoughts are with you as well," she told a media briefing alongside other officials.
A local newspaper reporter told BBC Radio 4's Today programme that the school was in lockdown during the shooting and that students were able to communicate with parents outside with their Apple watches.
Michael Kohn, a reporter with Bulletin newspaper, said the incident had left the parents stunned.
"This is a neighbourhood school. Parents are stunned. It's just something you don't expect to happen in Bend, Oregon. It's a mountain town,"
Schools in Bend have been closed on Friday. Officials said the community needed time to heal.
Around 450 children attend Silver Rail Elementary School, which has more than 40 adult staff members, police said.
According to the K-12 School Shooting Database, there were 235 shooting incidents at American schools last year and at least 140 so far this year.
Gun control advocacy group Everytown for Gun Safety has ranked Oregon 12th in the list of US states on the strength of its gun laws.
But gun violence rate in the state is near the national average at 14.2 deaths per 100,000 residents, according to the group.
