Two contractors and a member of the crew have been killed on board the Oceania Insignia following a fire.
The luxury cruise vessel was docked at the Caribbean Island of St Lucia when the incident occurred.
Some 656 passengers on-board the vessel were safely evacuated, with the remainder of the cruise cancelled.
A further crew member was in hospital, said Jason Lasecki, spokesman for the company.
The fire, which began in the engine room, was contained.
The US National Transportation Safety Board said it was sending officials to help with the investigation, which was being led by the Marshall Islands where the ship is registered.
The Insignia had departed San Juan, Puerto Rico, on Sunday for a ten-day cruise and was scheduled to arrive in Miami on December 17th.
The ship was built in 1998 and refurbished this year.
It re-joined the Oceania fleet in May after operating as a charter for two years, according to Oceania.
The Insignia has 400 crew members and its officers and staff are European.