USS Bonhomme Richard explosion and fire at Naval Base San Diego leaves 21 injured

The 840-foot amphibious assault ship caught fire on Sunday, resulting in a huge explosion while 160 sailors were on board the vessel, according to navy officials

Around 160 sailors were on board the amphibious assault ship when it caught fire, officials said.

At least 18 sailors and three civilians were wounded.

Video shows huge plumes of smoke pouring across the San Diego sky.

Mike Raney, a spokesman for the Naval Surface Force, US Pacific Fleet, said local, base and shipboard firefighting teams were all responding.

"All in-port ships have been contacted and directed to provide fire parties to possibly assist with firefighting efforts," Raney said.

The fire was reported at approximately 8.30am, the San Diego Fire Department said.

A huge fire and explosion has taken place on a US warship

Currently, two firefighting teams are on board the ship, Federal Fire San Diego Division Chief Rob Bondurant said in a statement.

"Federal Fire is rotating their crews aboard the ship with U.S. Navy firefighting crews from the waterfront to fight the fire in order to find the seat of the fire and extinguish it," he went on.

The origin of the fire is still unknown and is pending investigation.

The USS Bonhomme Richard is based in San Diego and was undergoing routine maintenance at the time of the blaze.

It has the capacity to deploy and land helicopters, smaller boats and amphibious vehicles.

The ship is about 840 feet long and when on active duty can carry around 1,000 sailors.