Police say it could have been a blown bus tire, or construction noise that caused the sound of an explosion in downtown Seattle.

But spokeswoman Renee Witt says inspections by officers, the bomb squad and a bomb dog found no evidence of a blast Thursday morning in a parking garage.

Witt says an earlier report of a hole in the structure was incorrect.

An explosion was reported just before 6 a.m. by the driver of a Metro bus passing the garage at Second Ave. and Union. Nearby streets were closed for a time for the investigation.

Witt says the bus driver later reported that a tire had blown out. She says there also was a report of something falling at a construction site.