SAN JUAN, Puerto Rico -- Islanders set up emergency shelters and airlines canceled flights as newly born Hurricane Earl churned toward the northern Caribbean on Sunday. Cruise lines diverted ships to avoid the storm's path.

The U.S. National Hurricane Center in Miami said Earl strengthened into a Category 2 storm with maximum sustained winds of 100 mph, and was expected to continue picking up steam as it moved near the northern Leeward islands.

Steady bands of rain began lashing islands including Antigua, where the Grand Pineapple Beach Resort on the north side battened down early for the night and tourists sought shelter inside their rooms.

Winds were heavy but had not caused any major damage, and the surf was higher than normal but not punishing, general manager Courtney Miller told The Associated Press by phone.

Center forecasters said Earl could strengthen into a major hurricane as soon as Monday -- probably while east of Puerto Rico. Major hurricanes are those Category 3 and higher.

People on several islands stuffed shopping carts with bottled water, canned food, milk, candles and batteries, while some tourists scrambled to board flights home. Others enjoyed the beach while they could.

"I'm just trying get a good suntan in while the weather is still cooperating," said Linda Curren of New York City, sunbathing on San Juan's Ocean Park beach as a few surfers paddled into pounding waves.

In Antigua, the V.C. Bird International Airport closed, while regional airlines LIAT and Winair suspended flights. Cruise ships diverted to other ports in the Caribbean and Mexico.

In St. Kitts and Nevis, authorities urged islanders to take all necessary precautions for the approaching hurricane, which is dwarfing the tiny island nations and territories of the northern Caribbean.

"We really don't want any loss of life, whether by persons who are careless or by security or emergency persons trying to rescue people," said Carl Herbert, head of the local emergency management agency.

Hardware stores were doing a brisk business in plywood and boards as jittery residents and employees of gleaming tourist hotels prepared to safeguard windows and doors.

"We haven't been hit for quite a few years, but you may never know -- this might be the time," said Ashley Benta, from the Antiguan town of Gray's Farm.

Fishermen and yacht owners tied down vessels in harbors scattered across the northern Caribbean.

"We're watching and waiting at this point," said June Otway, a manager of Puerto Del Rey, a 1,100-slip marina in northeastern Puerto Rico.

Earl could bring battering waves and a storm surge of up to three feet (one meter) above normal tide levels in some areas, according to forecasters. Heavy rains could cause flash floods and mudslides. Forecasters said Earl had several bands of thunderstorms wrapped around its center.

Late Sunday, Earl was about 50 miles east-northeast of Barbuda and headed west-northwest at 15 mph. Hurricane-force winds extended outward up to 45 miles from its center.

Warm ocean temperatures of 86 F are helping to fuel the storm.

Forecasters said there is a chance the hurricane could brush the U.S. Mid-Atlantic region toward the end of the week, with its closest approach to North Carolina on Thursday.

In any case, the U.S. East Coast is likely to see pounding surf.

As Earl approaches the U.S. Caribbean territories of Puerto Rico and the U.S. Virgin Islands, the Federal Emergency Management Agency said it stands ready to help.

"We continue to monitor the storm and stay in close contact with commonwealth and territorial emergency management officials in the region to ensure they have the resources to respond if needed," FEMA administrator Craig Fugate said.

Meanwhile, the Category 1 Hurricane Danielle was bringing dangerous rip currents to the U.S. East Coast. It was gradually weakening as it headed over the open Atlantic northeast of the British territory of Bermuda.