The teenage gunman who opened fire on an Oregon elementary school used a shotgun bought by his mother to kill four people, including three children, police revealed. 

Shots were fired at Silver Rail Elementary School at around 12.59pm as a 16-year-old gunman armed himself with a pump-action shotgun police say was purchased by his mom.

'We are stunned and heartbroken by this senseless tragedy,' Steven Cook, the Bend-La Pine Schools Superintendent, said. 

At least three children, aged five, eight and 11, were confirmed to have died as well as a teacher, Bend Police Chief Mike Krantz said.  

Cops arrived at the scene by 1.02pm and just moments later, the shooter was killed after being pursued by a 'hero' community member. 

Paramedics were seen setting up a staging area outside of the school, as a seven-year-old and a 54-year-old teacher were rushed to hospital. 

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Teen shooter used shotgun bought by his mother to gun down elementary school pupils

The 16-year-old suspect who fatally shot four inside Silver Rail Elementary School, including three children, used a gun purchased by his mom.

After gunfire broke out at around 1pm on Thursday, officials revealed that the teenager was armed with a long gun in the senseless attack.

The gunman, who was shot and killed by a heroic community member, used a pump-action shotgun bought by his mother, a law enforcement official revealed.

Of the six shot during the attack, three children, aged five, eight and 11, and one teacher were killed.

A seven-year-old and a 54-year-old teacher were transported to hospital with critical injuries.