In just three harrowing minutes, a 16-year-old gunman opened fire in the parking lot, stormed an elementary school and murdered three children and a teacher before a brave bystander shot him dead, according to police.

The teen shooter, who has not yet been identified, fired his mom’s pump-action shotgun at a man’s truck outside of Silver Rail Elementary School in Bend Oregon, with police receiving a call about an active shooter from the truck driver around 12:59 p.m., according to cops.

The gunman then ran towards the school and fired several shots at the locks, police said.

Then at 1 p.m., dispatchers in Deschutes County were flooded with calls reporting that a person had entered the school building and was shooting, prompting an emergency alert ordering all available law enforcement to the area.

Officers arrived at the school at 1:02 p.m. — but found that the suspect was already dead.

The massacre ended when the gunman was “shot by a community member who had seen [him] enter the school, pursued him into the school, and engaged him,” Bend Police Chief Mike Krantz told reporters at a press conference Thursday.

Three kids, ages 5, 8 and 11, and a teacher were fatally shot.

Another child, 7, and teacher, 54, were hospitalized in critical condition.

The shooter’s connection to the school is unclear, but officials confirmed he is a resident of Bend.