A cargo ship transporting 3,000 cars was abandoned in the middle of the Pacific Ocean on Tuesday after a massive fire broke out. As of Friday, the ship was still burning. The blaze may have been fueled by the vehicles’ lithium-ion batteries, which are notoriously difficult to extinguish once ignited.

A ship carrying about 3,000 cars to Mexico was abandoned in the middle of the Pacific Ocean after catching fire Tuesday, highlighting a growing risk to the transportation of electric vehicles.

The crew of the Morning Midas saw smoke first coming from a section of the ship containing electric vehicles, the company said.