Story highlights One person killed, four injured in accident on Harmony of the Seas

Accident happened during lifeboat drill while ship docked in the south of France

(CNN) Investigators are trying to determine how a lifeboat fell during a training exercise on the world's largest cruise ship Tuesday, leaving one crew member dead and four others injured.

A 42-year-old Philippines national died after the lifeboat fell about 33 feet (10 meters) during the exercise on board Royal Caribbean's Harmony of the Seas, which was docked in Marseille, France, Deputy Mayor Julien Ruas told CNN.

The four other crew members are being treated at a hospital.

Harmony of the Sea as it docked after the tragic deaths

Photos: Harmony of the Seas – Royal Caribbean's newest ship, Harmony of the Seas, makes its debut this weekend in Southampton, England. It's the world's largest cruise ship. Hide Caption 1 of 8 Photos: Can fit 6,780 guests – Harmony can fit up to 6,780 guests and 2,100 crew members. It's 1,188 feet long. In comparison, the Eiffel Tower is 984 feet tall. Hide Caption 2 of 8 Photos: The Ultimate Abyss – See those purple, squiggly things in the back of the ship? That's one of Harmony's biggest attractions: The Ultimate Abyss, which the cruise line calls "the tallest slide on the high seas." It takes guests on a 100-foot drop from Deck 16 to Deck 6. Hide Caption 3 of 8 Photos: Perfect Storm – Speaking of slides, there's a trio of multi-story water slides called Perfect Storm. One slide features a champagne bowl that swirls you around as you plunge down. Hide Caption 4 of 8 Photos: Suites at sea – Included among Harmony's 2,747 staterooms are top-end suites. "We have more suites at sea than any cruise line in the world," says Mark Tamis of Royal Caribbean International. Hide Caption 5 of 8 Photos: Bionic Bar – The Bionic Bar is staffed by two robot bartenders. They can make two drinks per minute and 1,000 drinks per day. Hide Caption 6 of 8 Photos: Wonderland – Specialty restaurant Wonderland, already a hit on a few other Royal Caribbean vessels, has gotten an upgrade. "It's been expanded on Harmony of the Seas," says Tamis. "It's actually a two-story venue that is going to be dramatically beautiful. " Hide Caption 7 of 8 Photos: Price tag – The cost? Prices start at $1,125 per person for a seven-night tour of the western Mediterranean. Hide Caption 8 of 8

The mammoth vessel first set sail in May, weighing 226,963 tons and accommodating 6,780 guests and 2,100 crew members.

Measuring 1,188 feet (362 meters), the ship is longer than the Eiffel Tower is tall. The Paris icon stands at 984 feet (300 meters).

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