LISBON (Reuters). Firefighters have been struggling to control a fire aboard a boat carrying luxury vehicles. It was adrift off Portugal’s Azores coast, a port official claimed, but it is not clear when the firefighters will succeed.

Felicity Ace was carrying around 4,000 vehicles (including Audis, Porsches and Bentleys), when it caught on fire at the Atlantic Ocean. All 22 crewmembers were evacuated from the ship that day.

“The intervention (to put out the blaze) has to be done very slowly,” João Mendes Cabeças, captain of the nearest port in the Azorean island of Faial, told Reuters late on Saturday. It’ll take some time.”

Lithium-ion batteries in the electric vehicles on board are “keeping the fire alive”, Cabeças said, adding that specialist equipment to extinguish it was on the way.

However, it was unclear if the batteries started the fire.

Volkswagen (DE) – The owner of the marques, didn’t confirm how many cars were onboard and stated on Friday that it was still waiting for further information. Ship manager Mitsui O.S.K. Lines Ltd didn’t immediately reply to our request for comment.

Cabeças previously said that “everything was on fire about five meters above the water line” and the blaze was still far from the ship’s fuel tanks. He said that it is becoming closer.

He said that the fire had spread farther down, and explained that the only way to stop it from spreading was by cooling the ship’s structures outside. It was too hazardous for crews to board.

They also cannot use water because adding weight to the ship could make it more unstable, and traditional water extinguishers do not stop lithium-ion batteries from burning, Cabeças said.

Although the Panama-flagged vessel will be taken to Europe and to the Bahamas by a tow truck, it’s not clear when.