SAN DIEGO -- Hundreds of sailors have isolated the fire ravaging the USS Bonhomme Richard down to two areas of the warship and a top Navy official said Tuesday it's possible the blaze could be extinguished over the next 24 hours.

Rear Adm. Philip Sobeck said the ship, which has been listing because of the water being poured on it to douse the flames, was stable and the structure was safe, giving a sign that it may still be saved.

“We have made significant progress,” he said.

Helicopters had dumped 1,200 buckets of water on the amphibious assault vessel, allowing crews to move further on board to fight the blaze. Tugboats were assisting from the waterline.

Sobeck said the fire's threat of moving toward the million gallons (3.8 million litres) of fuel on board had subsided because of the significant progress crews made overnight.

When asked if the blaze could be put out within 24 hours he said, “It's absolutely possible.”

The ship was emitting much less smoke than the previous two days, when acrid billows blanketed parts of the region.

The U.S. Coast Guard has hired an oil clean-up crew to put a containment boom in place that could be ready if any oil were to be spilled. It also halted boat and air traffic within a nautical mile of the vessel.

On Monday, health officials warned people to stay indoors as acrid smoke wafted across San Diego from one of the Navy's worst shipyard fires in recent years. At least 61 people, including 38 sailors and 23 civilians, have been treated for heat exhaustion, smoke inhalation and minor injuries. None were in the hospital Tuesday.

About 400 sailors along with Navy helicopters and firefighters poured water on the carrier-like ship, which erupted in flames Sunday morning.

Sobeck, commander of Expeditionary Strike Group 3, said fire temperatures had reached up to 1,000 degrees (538 Celsius), causing the mast to collapse and threatening the central control island where the captain operates the vessel. He said Tuesday there were now more than two decks between the fire and the fuel supplies.

The 840-foot (255-meter) amphibious assault ship was undergoing maintenance when the fire was first reported in a lower cargo area where seafaring tanks are parked. It appears to have started where cardboard boxes, rags and other maintenance supplies were being stored, Sobeck said.

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AP writers Christopher Weber and John Antczak contributed from Los Angeles.