The Washington State Patrol said a van repeatedly ran into a school bus on I-5 in downtown Seattle Friday morning.
It happened in the northbound lanes at Seneca Street shortly after 10 a.m.
Trooper Rick Johnson said it may have happened accidentally. He said the van rear-ended the bus, but then kept trying to push it forward. It then backed up and hit the bus again.
Police said the reason for the driver's behavior was not immediately known.
When a sergeant arrived at the scene, the van backed into his police car.
The driver of the van is in custody and the passenger ran from the scene, but police caught up with him at James Street and he was detained. Both are being checked out by medics.
Everyone on the bus is OK. About 40 children were on their way to Seattle Center.