Seattle Pacific University shooting: Aaron Ybarra arrested after shooting kills one and injuries three

Police say man was disarmed by a student as he was reloading

Medics wheel away a person shot at Seattle Pacific University on Thursday, June 5, 2014, in Seattle (AP)

A lone gunman opened fire in a building at a small Seattle university, killing one person and injuring three others before being disarmed by a student, police have said.

The Seattle Police Department said Aaron Ybarra, 26, had been booked into King County Jail on Twitter following the shooting on Thursday.

Police said a student building monitor at Seattle Pacific University overpowered the gunman after he entered the foyer at Otto Miller Hall. When he began reloading his gun, the student subdued him with pepper spray, Capt. Chris Fowler of the Seattle Police Department said.

Several other students then jumped on top of the gunman and pinned him down until police officers arrived. Police said the monitor's actions and the actions of others prevented the tragedy from becoming even more serious.

SPU President Daniel Martin told the Seattle Times the students who stopped the gunman "acted without regard to their own safety on behalf of others".

Medics wait behind cover after a shooting at Seattle Pacific University on Thursday, June 5, 2014, in Seattle. (AP)

A 19-year-old man was pronounced dead at the Harborview Medical Centre, where a critically injured 20-year-old woman was taken to surgery with a gun shot wound to her body, hospital spokeswoman Susan Gregg confirmed.

Two other people were hospitalised. A 24-year-old man and a 22-year-old man also sustained injuries. Ms Gregg said one of those two men was not shot.

None of the victims were immediately identified.

Police initially reported that they were searching for a second suspect, but later confirmed they believe the gunman was acting alone.

The university locked down its campus for several hours, and it alerted students and staff to stay inside. Some students were taking their final year exams in the same building that the shooter entered.

Student Jillian Smith, 20, said she was sitting an exam on the second floor of Otto Miller Hall when a lockdown was ordered.

She heard police yelling and banging on doors in the hallway. The professor locked the classroom door, and the 20 or so students sat on the ground, lining up at the front of the classroom.

“We were pretty much freaking out,” said Ms Smith. “People were texting family and friends, making sure everyone was OK.”

On Thursday evening, people packed into the First Free Methodist Church on campus and the surrounding lawn for a service.

Ashley Springer, 26, was in a classroom when a woman with a bullhorn came into the room and told them to lock the door, pull down the shades and turn out the lights.

The gun violence follows a spate of recent shootings on or near college campuses.

Seattle Mayor Ed Murray, who rushed to the scene after being alerted to the incident, highlighted previous mass shootings in the city and said: “Once again the epidemic of gun violence has come to Seattle.”

About 4,270 undergraduate and graduate students attend the private Christian university. Its 40-acre campus is in a leafy residential neighborhood about 10 minutes from downtown Seattle.

Additional reporting by agencies