The Coast Guard says a significant amount of gasoline may have spilled into San Francisco Bay after a tugboat struck a refinery pipeline.

The collision took place sometime during the night at the Tesoro Petroleum's Golden Eagle Refinery in Martinez, about 30 miles east of San Francisco.

It wasn't know how much gasoline spilled into the bay, but a Coast Guard spokesman says it's "a large amount."

Refinery crews and the Coast Guard are beginning clean up. There are no other details.

The Tesoro facility can refine 166,000 barrels of crude oil each day. The Golden Eagle refinery is the company's largest facility and the second-largest refinery in Northern California.