Police arrested a 22-year-old man Wednesday after he allegedly hit a pedestrian in a crosswalk at Kent-Meridian High School.
The 16-year-old boy suffered serious head injuries, police said, and crews took him to Harborview Medical Center in Seattle.
Officials with the hospital said the teen was in critical condition.
The boy was hit about 1 p.m. by the school at 10020 SE 256th St.
Police were working to identify him.