ALAMEDA, Calif. -- State, federal and environmental groups Monday were questioning whether the response to last Friday's spill of bunker fuel into San Francisco Bay was as rapid and thorough as originally claimed.

The crew of the Panamanian registered ship Dubai Star reported that fuel used to operate the tanker had spilled from a fuel transfer hose into the Bay at 6:48 a.m. Friday morning.

The Coast Guard says one of its boats arrived at the scene within half an hour and a helicopter was overhead just 90 minutes after the accident, which Petty Officer Levi Read called a timely response.

"At this point we are fairly satisfied with the response time," he said.

Deb Self, with the environmental group San Francisco Bay Keeper, said the crew of the Dubai Star may have downplayed the danger to the Bay.

"I just know the initial report was one or two gallons. When we have a slick that's one to two miles long within an hour or two, it's obviously not one or two gallons," Self said.

The spill turned out to be as much as 800 gallons of thick bunker fuel, which has since fouled six miles of Alameda County shoreline, killing at least a dozen sea birds and contaminating dozens more.

Deb Self wondered if cleanup booms could have been moved into place more quickly. "The reports I got coming in that day, it seemed like things were slow," said Self.

Mark McCaleb, with the California Office of Spill Prevention, said it's not always feasible to move booms in right away. "In a swift water environment, booming is not effective past about 1.5 knots," explained McCaleb.

Lt. Rob Roberts with State Fish and Game also had questions about the speed and effectiveness of the response.

"If it was text book, 100 percent, maybe nothing would have hit the shore. Maybe it would have. We don't know that until we're done with our investigation," Roberts said.

Roberts also had question about the deployment of booms.

"I'd be concerned if I didn't see booms in the water for the first four hours," said Roberts. "We're going over time lines right now."

Investigators said they should have answers to most of their questions by the end of the week.