TUKWILA, Wash. -- All lanes of southbound state Route 599 were blocked by a collision at the Metro bus barn in Tukwila Wednesday afternoon, according to Department of Transportation officials.

The Washington State Patrol, King County Sheriff’s Department, fire, rescue and a DOT Incident Response Team responded at the scene.

Traffic was backed up more than half a mile and drivers werer advised to choose alternate routes, such as state Route 509 and East Marginal Way.

DOT officials described the collision as serious.

The roadway was opened about an hour later.

The was no word on injuries.