The large number of electric vehicles on board a ship that is drifting ablaze in the Atlantic Ocean is complicating efforts to extinguish the fire, the Dutch experts contracted to salvage the vessel said Sunday.

It is unclear whether the blaze was caused by the electric cars, whose lithium-ion batteries have been known to catch fire, but the presence of burning batteries on board means SMIT Salvage, the company contracted to rescue the ship, is facing fire that spreads fast and cannot be fought with water alone, the company’s owners said.