A school bus crash blocking three northbound lanes of Interstate 5 in Federal Way caused a three-mile backup this morning.

Washington State Patrol Chris Webb said there were no children on the retired school bus and the driver was uninjured.

Troopers responded to the scene before the South 272nd Street interchange at approximately 7:50 a.m. Webb said the crash also involved four vehicles.

The driver who caused the accident attempted to move from the left lane to the HOV lane and struck the bus, causing the other vehicles to be involved, he said.

The driver who caused the accident was transported to Harborview Medical Center and may have serious injuries.