The incident occurred in the 4200 block of Lummi Shore Dr. at approximately 4:44 p.m.
According to state troopers, the boy had just gotten off the school bus and was crossing in front of the bus when the bus struck him.
The boy was airlifted to Harborview Medical Center in Seattle in critical condition.
Troopers believe lack of attention on the part of the school driver is to blame. They do not believe drugs or alcohol played a role.
The driver has not been charged.