leak in a fuel oil return line was the cause of an engine-room fire  that disabled a Carnival cruise ship last weekend, a U.S. Coast Guard official said Monday. The fire left the Triumph disabled in the Gulf of Mexico for five days and the 4,200 passengers and crew without power or working toilets.

A spokesman from Carnival Cruise Lines said Monday that the company is in agreement with the Coast Guard’s findings.

The investigation into the cause of the accident and why the ship was disabled for so long will take up to six months, Cmdr. Teresa Hatfield said in a call with reporters. The ship was towed to port in Mobile, Ala., and arrived late Thursday night.

A Bahamian maritime agency is leading the investigation, which also includes the U.S. Coast Guard and National Transportation Safety Board. The cruise ship is a Bahamian-flagged vessel.

Hatfield said investigators have been with the 900-foot-long, 14-story ship since it arrived in port. Passengers and crew have been interviewed and a forensic analysis performed as part of the probe. Coast Guard and NTSB investigators will stay with the ship likely until the week’s end, then continue working from their offices.

One Houston woman who was a passenger on the ill-fated Triumph voyage has already filed a lawsuit claiming Carnival was negligent and place passengers in hazardous conditions in the aftermath of the fire. She is seeking more than $75,000 in damages.

Schechter, Shaffer & Harris, L.L.P., Accident & Injury Lawyers is a cruise ship injury law firm in Houston that represent cruise passengers and crewmembers who have been injured while on cruise vessels.