A ruptured fuel line on a Panamanian-registered tanker released oil into San Francisco Bay before dawn on Friday.AFP

View of ruptured oil line

The US Coast Guard said the source of Friday's spill, from the tanker Dubai Star, was contained within hours and that a cleanup was under way. AFP

Anchored oil tanker

The oil tanker Dubai Star sits anchored in the San Francisco Bay October 30, 2009 in San Francisco, California.AFP

Oil boom extends from the tanker

An oil boom extends from the rear of the oil tanker Dubai Star as it sits anchored in the San Francisco Bay October 30, 2009 in San Francisco.AFP

Spill occurred across the San Francisco bay

The spill occurred near the Oakland Airport, across the bay from San Francisco.AFP

Amount of spill unknown

It is unknown how much oil was spilled into the bay and crews are beginning to start clean up operations.AFP

Aerial view of the tanker

The Dubai Star oil tanker is seen in an aerial view off the coast of San Francisco.AP