MOBILE, Ala. (AP) — A Coast Guard official said Monday that the cause of the engine-room fire on the Carnival cruise ship Triumph was a leak in a fuel oil return line.

Cmdr. Teresa Hatfield gave the description in a conference call with reporters and estimated that the investigation of the disabled ship would take six months.

Hatfield said the Bahamas —where the ship is registered, or flagged — is leading the investigation, with the Coast Guard and National Transportation Safety Board leading U.S. interests in the probe.