LOS ANGELES (AFP) - Four people were wounded in a shooting on a Seattle university campus on Thursday, police and fire officials said, adding that a suspect reported on the loose had been detained.

The Seattle Fire Department said four gunshot victims were taken to hospital "with wounds varying from minor to life-threatening." Media reports said two suspects were in custody.

A man and a woman suffered "life-threatening injuries," while another man and another woman were in "stable" condition, police said.

The shooting took place on the campus of Seattle Pacific University, the northwestern US city's police department said on its Twitter feed.

Police at first said one suspect was detained and another on the loose, but a short time later tweeted: "The suspect is in custody. There are no outstanding suspects being sought."

They did not immediately confirm media reports that there were two suspects.

KIRO TV said the two suspected gunmen were reported in separate buildings at the campus, citing witnesses as saying one came into a classroom and opened fire.

The shooting came less than two weeks after a mentally unstable 22-year-old opened fire at a campus in Santa Barbara, California, killing six people before turning the gun on himself.

School shootings have become a tragic periodic occurrence in the United States in recent years.

They include the December 2012 massacre in Newtown, Connecticut that left 20 small children dead, and the Virginia Tech college shooting in April 2007 in which 33 people died, including the lone gunman.