The captain of the Solong cargo ship who was arrested after crashing into an oil tanker off the English coast is a Russian national, the vessel’s owner said Wednesday, as maritime experts search for answers.

The police in Britain detained the ship’s captain on suspicion of gross negligence after it crashed into an oil tanker that was being operated by the U.S. Navy.

A port official said he was told the North Sea collision produced "a massive fireball" and the cargo ship's owner said one crew member was missing.