A student opened fire at his Washington state high school on Friday, killing one person, wounding at least four others and spreading panic among students who scrambled across fields and parking lots to safety, police and hospital officials said.

The shooter at Marysville-Pilchuck High School, about 30 miles north of Seattle, acted alone and was now dead, Marysville Police Commander Robb Lamoureux told reporters.

"We are confident that there was only one shooter and that the shooter is deceased but we do need to clear each building and make sure that was the case," Lamoureux said.

Authorities said they did not yet know what may have motivated the assailant and declined to release the suspect's identity.

Local television station KIRO showed images of students running from school buildings, crossing a sports field with their hands in the air as officers with rifles ran across the school yard.

Police and hospital officials said at least four, all "young people," were wounded, three of them critically and were in surgery.

A spokeswoman for Harborview Medical Center in Seattle said the hospital was expecting to receive one patient from the shooting but had no word on that person's condition.

The school district said students were being sent to a nearby church from where buses would take them home after the school was put on lockdown.

Parent Jerry Holston told CNN that his two children had contacted him by phone following the gunfire and were not wounded.

Holston said son, Adam, called him immediately following the shooting, yelling: "Dad, dad, hurry, someone is shooting. Please come."

NBC News reported that President Barack Obama had been briefed about of the situation.