Investigators want to know whether a ship pilot under investigation in San Francisco Bay's biggest oil spill in nearly two decades initially played down the damage to his vessel, Coast Guard officials said Monday.

Immediately after the Cosco Busan struck the Bay Bridge last week, Capt. John Cota quickly radioed authorities to report the vessel had "touched" the bridge, according to an official with knowledge of the investigation.

"Traffic, we just touched the delta span," Cota said, according to the official, who spoke on condition of anonymity because of the ongoing criminal probe. Cota was referring to one of four supports beneath the bridge's western section.

The impact did not damage the bridge, but it opened a 90-foot gash in the hull of the ship and ruptured its fuel tank, dumping 58,000 gallons into the bay, fouling miles of coastline and killing dozens of shorebirds.

"The comments made or the actions taken by individuals are all things that they could be held accountable for," said Rear Adm. Craig Bone, the top Coast Guard officer in California.

Said Sr. Chief Petty Officer Keith Alholm, a Coast Guard spokesman: "One of the aspects of the investigation is, were the reports made accurate" after the collision.

But Cota's lawyer said his client did not immediately realize the severity of the crash.

"He has told me you could hardly feel anything on the ship and he must have assumed from that that there wasn't much damage," John Meadows said. "The ship didn't roll. There wasn't a loud sound."

Federal prosecutors investigating the accident are focusing on problems involving management and communication between the officers on the ship's bridge at the time of the crash. Among other things, the ship was under new ownership and management, and the crew's experience on the vessel appears to have been limited, officials said.

Crew members were questioned on board beginning Sunday, said Coast Guard attorney Christopher Tribolet.

Any charges — civil or criminal — would likely fall under the negligence provisions of the Clean Water Act and the U.S. transportation code, Tribolet said.

The Coast Guard notified the U.S. attorney's office Saturday about problems involving coordination between the officers on the ship's bridge at the time of the crash.

Coast Guard officials declined to comment Monday on Cota's radio transmission and how it relates to the investigation. Scott Schools, the acting U.S. attorney for Northern California, confirmed that his office was asked to investigate.

The bridge personnel included the helmsman, watch officer, and ship's master, as well as Cota, who is among the most experienced of the seamen who guide ships through the bay's treacherous waters.

At least six members were found to have immigration or visa issues, authorities said. Foreign crew members on any ship in U.S. ports need the permission of U.S. Customs and Border Patrol to disembark, Tribolet said.

Cota and his lawyer were slated to meet for the first time Monday with investigators from the National Transportation Safety Board, which is conducting its own probe that will include an examination of the Coast Guard's response.

Cota has also met several times with Coast Guard investigators, Meadows said.

Darrell Wilson, a representative for Regal Stone, the Hong Kong-based company that owns the Cosco Busan, declined to comment on the investigation.

On Monday, House Speaker Nancy Pelosi, D-Calif., and several members of the Bay Area's congressional delegation joined Coast Guard Commandant Adm. Thad Allen and Rear Adm. Craig Bone along the bay.

Pelosi questioned Bone about the Coast Guard response, specifically the time lapse in releasing the full extent of the spill to the public. Agency officials learned the true extent of the spill several hours before local officials and the public were notified.

"We have very, very serious concerns about how this transpired and the timing," Pelosi said. "There are many questions that have been raised."

Earlier, Allen defended his agency's response to the spill while pledging a full investigation.

"On the surface it would appear that we did everything by the book in this case as far as responding," Allen told The Associated Press while en route from Washington, D.C., to survey the damage.

"However, having done this work for over 36 years, nothing is as it seems at the start," he said. "We need to recover all the information, make sure all the facts are established."

Allen said it may have taken time to figure out the extent of the spill partly because gear used to measure how much fuel is in the oil tank was damaged by the crash. He also noted the poor visibility at the time — a quarter-mile to an eighth-mile in fog.

"You don't turn 900-foot vessels on a dime," he said. "And given the visibility at the time, I think it would be difficult to assess whether or not the bridge itself was visible."

More than 12,000 gallons of oil had been recovered by Monday, but much never will be, the Coast Guard said. Some will evaporate or dissipate and be absorbed into the environment.

Wednesday's spill was the biggest since 1988, when 400,000 gallons of oil spilled after a Shell refinery drain line broke. Another spill in 1996 poured 40,000 gallons of oil into the bay from a military vessel near Pier 70.