Harmony of the Seas was docked in the French port of Marseille when the incident happened
One person has died and four others injured after a lifeboat became detached from the world's biggest liner, Harmony of the Seas.
The 227,000-ton cruise liner, operated by Florida-based Royal Caribbean - was docked in the French port of Marseille when the incident happened, emergency services said.
"One person is dead and four are injured, including two whose lives are in danger," said a spokesman for the fire service.
All five were reportedly in the lifeboat when it "became detached", he added.
It is unclear if they were taking part in a safety drill at the time.
The ship - dubbed "Europe's biggest hotel" - cost $1bn and has the capacity to carry 6,780 passengers and 2,100 crew members.
It has been compared to a floating city with more than 2,747 staterooms, 20 restaurants, 23 swimming pools and a park with more than 10,000 plants and 50 trees.
It also boasts what it describes as seven neighbourhoods which include a cinema, promenade, sports and youth zones, an entertainment palace and spa and fitness centre.
At 362 metres long, the 16-deck ship is bigger than the Eiffel Tower and is the widest cruise ship ever built at 65 metres.