A 16-year-old teenager opened fire at an elementary school in Oregon, US, killing three children and a teacher, while leaving two others seriously injured.

A 9-year-old student who was in a nearby classroom at the time of the shooting described the situation as follows.

[Kalani Zurn / Surviving Student : Vice Principal Thomas ran into the hallway, screaming, 'Get in a classroom!' or 'Just hide!' We went into that room and hid for about 30 minutes, and we heard multiple gunshots.]

The shooting occurred around 1 p.m. on the 15th local time at Silver Rail Elementary School in Bend, Oregon.

According to police, the gunman was a 16-year-old male former student of the school. He climbed a fence at the back of the school, broke the glass of a locked entrance door with a shotgun, and entered the building.

The gunman immediately entered a classroom containing special education students and opened fire.

Police estimate that the perpetrator fired up to 15 rounds.

The shooting killed three children aged 5, 8, and 11, along with 25-year-old teacher Megan Lambert.

A 7-year-old student was severely injured and is receiving treatment, while a 54-year-old teacher was also seriously injured but is in stable condition with no threat to life.

During the shooting, responses from a teacher and a parent helped prevent further casualties.

Bend, Oregon Police Chief Mike Krantz stated that the teacher's actions averted a greater loss of life.

[Mike Krantz / Police Chief, Bend, Oregon : I want to highlight the heroic actions of another individual. A teacher inside the classroom threw a cell phone at the shooter and then physically rushed him, struggling to disarm him. This teacher was not injured and prevented further loss of life.]

A 36-year-old parent who has two daughters at the school also stepped in to subdue the gunman.

After spotting the teacher and the gunman wrestling, the parent fired multiple shots at the gunman, who died at the scene just before police arrived.

Police found a shotgun along with 44 rounds of unused ammunition at the scene.

Authorities are continuing to investigate how the gunman obtained the firearm and ammunition, as well as the motive behind targeting his former school for the shooting.

(Produced by SBS Digital News)