(FOX News) --
DEVELOPING: A high school student in Marysville, Wash., opened fire in the school cafeteria Friday morning, injuring at least six before killing himself, police and witnesses said.
A local hospital said it had received three victims in critical condition after the shooting, which began around 10:45 a.m. PT at Marysville-Pilchuck High School, located 35 miles north of Seattle.
"I heard people start screaming," Jordan Luton, a freshman who played on the high school football team with the gunman and was present during the shooting, told Fox News' Shepard Smith. "People dropped to the ground."
Luton, who was about two tables away, said the shooter didn't say anything, and the shooting lasted about a minute. He believed a 9 millimeter gun was used.
Local news reports say there may be two other possible fatalities.
Marysville police Cmdr. Robb Lamoureux told reporters that the incident remained an "active situation" and urged people to stay away from the high school campus.
"We have not cleared the entire building yet," Lamoureux said. "I don't know the status of all of the students."
Lamoureux added that a local church was serving as a reunification spot for students and their parents.
As details of what happened inside the building trickled out, students could be seen exiting the school with their arms raised.
The Marysville School District said in a statement that "Marysville-Pilchuck High School is currently in lockdown due to an emergency situation. Police and emergency services have responded."
All after-school activities were canceled, the district said. Marysville is a city of about 60,000 in Snohomish County.
The Times reported that police were searching the school with guns drawn. Seattle FBI said personnel were on their way to the scene to help with the investigation.
The last school shooting in the region happened at Seattle Pacific University, where a gunman killed one student and wounded two others on June 5.
The Associated Press contributed to this report.