Police boats combat a fire aboard the amphibious assault ship USS Bonhomme Richard at Naval Base San Diego on Sunday.

U.S. Navy/U.S. Navy via Getty Images

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U.S. Navy/U.S. Navy via Getty Images

Police boats combat a fire aboard the amphibious assault ship USS Bonhomme Richard at Naval Base San Diego on Sunday.

U.S. Navy/U.S. Navy via Getty Images

A fire continues to burn on a U.S. Navy warship docked in San Diego a day after it broke out, injuring at least 57 people and sending giant plumes of smoke into the sky.

An explosion rocked the USS Bonhomme Richard on Sunday morning while in port at San Diego Naval Base. Of approximately 160 people on board at the time, 34 sailors and 23 civilians were injured, according to Naval Surface Forces.

Five people are still hospitalized and in stable condition as of Monday morning. The injuries were minor, the Navy said, and include heat exhaustion and smoke inhalation.

Firefighters worked on board the ship overnight and also used helicopters to try to extinguish the flames, the Navy said.

The cause of the explosion and fire remain under investigation. Rear Adm. Philip Sobeck told The San Diego Union-Tribune that the Navy believes the fire started in a lower cargo hold used to store marine equipment and vehicles.

The USS Bonhomme Richard could burn for days, “down to the water line,” San Diego Fire Chief Colin Stowell told CNN.

Federal Fire San Diego has led the effort, with crews rotating on board the ship. It’s working with San Diego Fire-Rescue.

Navy tugboats were continuously combating the fire from the bay as of Sunday afternoon, Federal Fire San Diego Division Chief Rob Bondurant.

Chief of Naval Operations Adm. Michael Gilday called the fire a “terrible tragedy.”

“Our thoughts and prayers are with our BHR Sailors, their families, and our emergency responders who continue to fight the fire,” he said in a statement. “Godspeed.”

The San Diego office of the National Weather Service reported a “very strong smell of smoke” at its office in Rancho Bernardo. “South winds from the coastal eddy are likely spreading smoke from USS Bonhomme Richard north along I-16 corridor,” NWS said on Twitter. It said the smoke would likely lift as temperatures heated up through the day.

The 23-year-old USS Bonhomme Richard is designed to deploy Marines in amphibious assaults.

The total cost of the warship is estimated to be $761 million, according to the Federation of American Scientists. It has been docked in San Diego undergoing nearly $250 million worth of maintenance, modernization and repairs.

Because of the renovation work, only a fraction of the ship’s crew of about 1,000 were on board when the fire broke out.

It’s not clear how much damage the ship has sustained, though Sobeck told the Union-Tribune that the Navy was “absolutely going to make sure it sails again.”

He added: “Right now we’re going to fight the fire and then we’ll work on understanding what exactly happened to make sure she sails as best as possible in a very near time.”