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.

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.

An oil tanker reportedly on fire in the North Sea after colliding with a cargo vessel. Lifeboats and a coastguard helicopter were called to the collision in the Humber Estuary on Monday morning, believed to involve a US-flagged tanker called the MV Stena Immaculate.