At least four people were killed and an unknown number wounded late Friday during a shooting at a mall in the state of Washington, with the suspect still on the run, police said.

Washington State Patrol District 7 spokesman Sergeant Mark Francis described the suspect in the shooting at Cascade Mall in Burlington, in the US Pacific Northwest state as a "Hispanic male wearing grey."

"EMS starting to enter to attend to injured inside Mall w/ police escort and after initial clearance," Francis said on Twitter shortly before 8:30 pm (0330 GMT), referring to emergency medical services. 

"Once EMS gets in, holding out hope that the number confirmed goes down."