A gunman killed one person and wounded at least three others Thursday at a university in Seattle before he was disarmed by a student security guard.

Police said the lone gunman entered into Otto Miller Hall, an engineering building, at the Seattle Pacific University and opened fire.

The gunman was held down and arrested by several officers after the student subdued the man as he was reloading.

The suspect was not immediately identified.0 Witnesses at the scene said the suspect appeared to be in his mid-30s and might not be a student at the school. A professor said ammunition rounds he saw scattered on the floor appeared to be from a shotgun.

A spokeswoman of the Harborview Medical Center said a man in his 20s died and a critically injured 20-year-old woman was taken to surgery. A 24-year-old man and a 22-year-old man were listed in stable condition at the same hospital.

With over 4,200 students, the Seattle Pacific University is a private Christian liberal arts college about 6 km north of downtown Seattle.

"It's a day of tragedy and loss," Seattle Mayor Ed Murray told reporters at the university. "Once again, the epidemic of gun loss has come to Seattle - the epidemic that has been threatening this nation."

The shooting came after Elliot Rodger, a 22-year-old student, killed six and injured seven people before turning his gun on himself last month in Isla Vista near the University of California in Santa Barbara.