SAN FRANCISCO – A harbor pilot under investigation in San Francisco Bay’s biggest oil spill in two decades initially believed the damage to his ship was minor, radioing that the vessel had just “touched” the Bay Bridge, his lawyer said Monday.

In fact, Wednesday’s collision ripped a gash in the fuel tank of the Hong Kong-based Cosco Busan, unleashing 58,000 gallons of thick, toxic fuel oil that was still being cleaned up.

Captain John Cota “has told me you could hardly feel anything on the ship and he must have assumed from that that there wasn’t much damage,” attorney John Meadows said. “The ship didn’t roll. There wasn’t a loud sound.”

Cota quickly radioed authorities over an open radio network to report the ship had “touched” the bridge, according to an official with knowledge of the investigation.

“Traffic, we just touched the delta span,” he 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 spill, initially reported at just 140 gallons, ended up being hundreds of times worse. The collision caused no structural damage to the bridge, but the fuel has fouled miles of coast, closed nearly two dozen beaches and piers and killed dozens of seabirds.

The ship was being detained at the Port of Oakland. Crew members were questioned on board the vessel 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.

Capt. William Uberti, the Coast Guard commander for the bay region, declined to elaborate, except to say: “It was just the way that everybody interacted” on the bridge.

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 water.

All 26 crew members remained on board Monday, said Henry de La Garza, a spokesman for Regal Stone Ltd., the Hong Kong-based company that owns the Cosco Busan.

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. He declined to release a statement his client made to investigators.

Darrell Wilson, a representative for Regal Stone, 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.”

AP writers Erica Werner and Jason Dearen contributed to this report