A blaze that broke out in the engine room of a towing vessel on the Lower Mississippi River was probably caused by an engine lube oil leak that ignited off a hot surface near the starboard main engine turbocharger. That’s according to the National Transportation Safety Board (NTSB), which has completed its investigation into the September 12, 2018 incident.

The towing vessel Jacob Kyle Rusthoven was pushing nine barges southbound near West Helena, Arkansas when the fire began. As it spread, three of the barges broke away from the tow, and one rolled over and lost its cargo.

All six crewmembers abandoned the vessel onto the barges, from where they were rescued by a Good Samaritan vessel. Due to smoke inhalation, the crew was later sent to the hospital and discharged the same day. No pollution was reported. The Jacob Kyle Rusthoven, valued at an estimated $1.5 million, burned completely.

The NTSB said the crew’s failure to activate the engine fuel supply shutoffs and secure open doors ventilating the engine room contributed to the severity of the fire.