San Francisco ? 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.