U.S.-based maritime management firm Crowley, which operates the Stena Immaculate, said the tanker “sustained a ruptured cargo tank containing Jet-A1 fuel,” when the container ship struck it, triggering a fire and “multiple explosions onboard,” with fuel released into the sea. It said all 23 mariners on the tanker were safe and accounted for.

U.K. police have opened a criminal investigation into a collision between two ships in the North Sea and have arrested a man on suspicion of manslaughter.