Hurricane Gonzalo grew into a major Category 3 storm Tuesday and is expected to strengthen further as it heads toward Bermuda after killing a man in the Dutch Caribbean territory of St. Maarten, authorities said.

The storm had top sustained winds of nearly 115 mph and was centered about 770 miles south of Bermuda on Tuesday afternoon, said the U.S. National Hurricane Center in Miami. It was moving northwest at 13 mph.

Forecasters said Gonzalo could become a powerful Category 4 hurricane Wednesday as it spins over open waters through Friday on a track toward Bermuda. Category 4 storms have sustained winds of at least 130 mph with the potential to cause catastrophic damage.

"Folks in Bermuda are going to need to start paying attention to this thing," Dennis Feltgen, a National Hurricane Center meteorologist, said by phone.

Gonzalo was blamed for the death of an unidentified elderly man who was aboard a boat in St. Maarten's Simpson Bay Lagoon, which looked like a ship graveyard Tuesday with several masts protruding from the water. Acting Coast Guard Director Wendell Thode said 22 of the 37 boats destroyed by the storm were in the lagoon.

"Most of the boats that are destroyed are completely under water," he said.

Authorities were searching for a man last seen on a dinghy near the French Caribbean territory of St. Martin and another man last seen standing close to a harbor in St. Barts, said Matthieu Doligez, general secretary of the prefecture in St. Martin.

Police Chief Peter de Witte said no one was reported missing in St. Maarten.

Most of the Dutch Caribbean territory was without water and electricity Tuesday, and residents reported losing roofs, doors and windows.

Susan Cuniff, who helps run the Liberty Inn hotel in front of Simpson Bay lagoon, said people were not prepared for a hurricane.

"It was a big storm, much bigger than people predicted, and a lot of bad things happened," she said in a phone interview. "Boats crashed into each other and trees were downed and even the zoo was decimated."

Amy Arrindell, vice president of the St. Maarten Zoological and Botanical Foundation, said the St. Maarten Zoo was heavily damaged but no animals escaped or died. She said trees were uprooted, the petting zoo was destroyed and the animals' enclosures were flooded.

"There is major damage to the structure," she said. "It is total devastation."

As Gonzalo headed northwest over open waters, it churned up heavy surf in Puerto Rico, the U.S. and British Virgin Islands, the Turks and Caicos Islands and the southeastern and central Bahamas.

Officials said flights departing Bermuda on Thursday, Friday and Saturday were fully booked. Robert Palmer, a spokesman for Canadian carrier WestJet Airlines Ltd., said only a few seats were available for flights Tuesday and Sunday to Toronto.

"It's likely we've seen a spike in demand with word of the storm approaching," he said.

Several hotels reported being fully booked with a mixture of tourists and locals.