Twenty-one people suffered minor injuries in an explosion onboard USS Bonhomme Richard leading at Naval Base San Diego, military officials said.

The fire was reported just before 9 a.m. on USS Bonhomme Richard, said Mike Raney, spokesman for Naval Surface Force, U.S. Pacific Fleet.

Raney said 17 sailors and four civilians were put in hospital care with "non-life-threatening injuries" in a brief statement. No further details were available.

Officials said previously that at least one person was getting treatment for smoke inhalation, Associated Press reported.

The statement was also quoted in a report on Fox News. "All in-port ships have been contacted and directed to provide fire parties to possibly assist with firefighting efforts," it read.

The officials are now doing investigations as to the cause of the fire. It was also not known immediately where the blast and fire started in the 840-foot vessel.

San Diego is the home port of USS Bonhomme Richard, and the ship was going through maintenance at the time of the fire.

Federal Fire San Diego Division Chief Rob Bondurant said two teams were still fighting the fire on the ship at 4:15 p.m., San Diego Union-Tribune reported.

The crews were rotating aboard the ship. Navy firefighting crews were also at the waterfront to fight the fire and looked for the fire source, Bondurant said.

Bondurant said Navy Region Southwest tugs were also fighting the fire from the bay.

At the time, there were 160 sailors and officers on the ship. Raney said this is a far smaller number than the thousand people the ship usually boards on its active duty.

All members of the crew were accounted for, said Admiral Mike Gilday, Chief of Naval Operations. Gilday said he is grateful for the fast response of the firefighters on the ship.

At least a dozen fire engines and trucks were by the pier. At least six ambulances were inside.

The fire department said there were around 150 firefighters working on the blaze and there was also a fire investigator dispatched.

Craig Hooper of Forbes said the fire could've been preventable and the navy had been witness to many fires with ships undergoing maintenance. Hooper said there may be issues with maintenance safety on the fleet.

Flames sent a huge cloud of dark smoke

The fire was caught on photos showing a huge cloud of smoke around the naval base.

As federal fire crews continued to fight the fire on the smoking ship, there were warnings on air quality and safety issues that went on into the early evening.

Around 5:30 p.m., all personnel who were not first responders were issued a shelter-in-place order alert. People from the wet-side of north of Pier 5 were issued the order to stay put until further notice.

As the day went on, smoke and fumes that turned from black to gray and white came from the ship.

National City issued an advisory at 2:30 p.m. telling residents to stay at their homes or other indoor establishments because of the possible health and safety issues brought by the smoke.

Machete Beer House, a National City business, only let to operate outdoors due to health orders in light of COVID-19 was forced to close for the day because of the plume.

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