WASHINGTON – California senators, both Bay Area Democrats, attacked the U.S. Coast Guard on Wednesday for what they called a litany of problems contributing to last week's oil spill in the San Francisco Bay.

"It's outrageous," exclaimed Sen. Barbara Boxer. "Heads have to roll. This isn't right."

Sen. Dianne Feinstein questioned whether the response capabilities of the Coast Guard have diminished since it was integrated into the Department of Homeland Security.

"There is so much emphasis on terrorism," Feinstein said.

Their comments came at what was billed as a Senate Commerce Committee briefing on last week's shipping accident, which dumped as much as 58,000 gallons of fuel oil into the water. But with Coast Guard and other government officials facing questions from irate senators, the hourlong session had the feel of a tough congressional hearing.

Coast Guard Commandant Adm. Thad Allen said only a thorough investigation would reveal all the faults. While it's unclear whether the Bay Area's spill response plan has problems, Allen said, in this instance "the question is whether it was followed."

The spill occurred when the Cosco Busan cargo ship struck a support for the San Francisco-Oakland Bay Bridge, rupturing one of two 500,000-gallon fuel tanks. The spill was first reported as a minor 140 gallons, and 12 hours went by before the Coast Guard learned that it was much larger. The ship may have been traveling too fast in heavy fog, even after losing its radar. Meanwhile, witnesses said, response steps were not followed, drug and alcohol testing of some crew members was delayed, there was poor coordination with the contractor in charge of cleaning up the mess, and the oil slick spread.

"The response was like fleas on an elephant: It was minuscule compared to what was demanded," said Deb Self, executive director of Baykeeper, a watchdog organization.

Feinstein sought to reveal lapses in federal regulations that might have contributed. When she asked whether the Coast Guard has authority to order ships to slow down, Allen replied, "That authority does not currently exist." When she asked whether laws requiring a second hull to double the protection of fuel tanks on cargo ships would help, Allen said, "It is something we should look at."

Joseph Osterman, managing director of the National Transportation Safety Board, said investigators are trying to piece together what happened on the ship before the accident. He said the vessel was under temporary command by a pilot who communicated in English to the ship's master, who then spoke to the crew in Chinese. Osterman said the NTSB has interviewed the pilot but not the master because of "some complications" related to a criminal investigation.

Pilots knowledgeable about local waterways typically command ships until they reach open waters. Boxer cited reports that this pilot had been reprimanded as recently as last year for running a ship aground, asking the Coast Guard why his license had not been revoked.

"Jurisdiction," said Rear Adm. Brian Salerno, assistant commandant for marine safety. The pilot was operating under a state license, Salerno said.

The Coast Guard expects to complete its investigation in 90 days. NTSB investigations can take a year or longer.