The Contship Jet, a container ship chartered by ZIM Integrated Shipping Services, was struck by at least three maritime drones and sank off Bulgaria on Wednesday. The Liberian-flagged vessel was sailing from Haifa, Israel, to Constanța, Romania, when it was attacked within Bulgaria’s exclusive economic zone.

Bulgarian naval and border police vessels rescued all 18 crew members. The crew included 14 Filipinos and four Ukrainians.

The ship sank with all 421 containers on board. They reportedly included hazardous materials such as lithium-ion batteries and flammable liquids.

ZIM said the vessel was not company-owned and that it expected minimal financial damage. The company said it was working to secure a replacement ship to maintain service.