Bend (United States) (AFP) – A teenager shot and killed three children and a teacher on Thursday at an elementary school in the US state of Oregon, police said, adding the assailant was later killed by an armed bystander who pursued him into the building.

Officers rushed to Silver Rail Elementary in Bend, a city of about 100,000 in the nation's northwest, after reports of a shooter on campus on Thursday afternoon.

The three children who died on the scene were aged five, eight and 11, said Bend police chief Mike Krantz. Another child and a teacher were being treated for critical injuries after the shooting.

The United States, where firearms are readily available, has a long and painful history of gun violence, with thousands of people killed every year. It has the highest rate of gun-related deaths among all developed nations.

People gathered in the city's Drake Park on Thursday evening for a candelight vigil remembering the victims.

"I'm in total complete shock, and scared and sad," said Betsy, who did not give her last name. She spent around 10 minutes contemplating a circle of candles and flowers.

"It's awful, but it also has brought people together," she told AFP.

Krantz, the police chief, told journalists that the department first learned of an active shooter after a call from a person who reported being shot at multiple times by a person carrying a long gun.

Dozens of emergency calls then reported that a shooter had entered the school and all law enforcement in the area were called to the scene, the chief added.

Officers arrived at 1:02 pm local time (2002 GMT) within minutes of the calls, he said.

"Moments later, an officer reported that the suspect had been shot by a community member who had seen the suspect enter the school and pursued him into the school and engaged him," Krantz said.

"Our officers entered the building and confirmed the suspect was dead."

One seven-year-old and one 54-year-old teacher with critical injuries were transported to a local hospital, he said.

The police chief said the investigation was in its early stages, but told the press conference it appeared "the shooter had forced their way into the school by shooting at locked doors."

He added that the 16-year-old shooter was a Bend resident.

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