The Hoegh Autoliner car carrier that sustained an explosion on Thursday afternoon at Florida's Blount Point Marine Terminal is still on fire but the blaze has been brought under control, according to company and fire department officials.

The explosion happened on the seventh deck of 4,900-ceu Hoegh Xiamen (built 2010) shortly before 1600 hours while the ship was still in the Jacksonville port. It had just taken on about 2,000 vehicles.

"The fire is under control and contained at this time although it is still burning due to access issues," Jacksonville Fire and Rescue Department said on its Twitter feed.

All 21 crew members evacuated the ship but eight injured firefighters, four of whom received serious burns, were taken to local medical facilities.

"The fire aboard our vessel, Hoegh Xiamen, is still burning. Efforts to extinguish the fire are progressing and remain ongoing," the Norwegian owner said on Sunday in an update on its website.

"Firefighters with Jacksonville Fire and Rescue Department and specialist marine firefighters with Resolve Marine Group continue to work to extinguish the blaze on several decks, with an ongoing focus on cooling the vessel’s exterior."

Fire tugs and a "high-capacity pump" are spraying water on the vessel to keep it cool, the company said.

There has been no report of any pollution, which is being continually monitored while containment booms encircle the vessel as part of an effort to protect the environment, Hoegh Autoliners said.

“We are continually grateful for the assistance of the state of Florida, the US Coast Guard, the Port of Jacksonville and especially the firefighters whose ongoing hard work and expertise have brought the fire under control," chief executive Thor Jorgen Guttormsen said in a statement.

"Our thoughts and prayers remain with the firefighters who sustained injuries during the initial response to the fire and we wish them a speedy recovery.”