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Tropical Storm Chris continued to gain strength Tuesday as it approached the eastern edge of the Caribbean, prompting a run on groceries and gas as people prepared for the third named storm of the Atlantic hurricane season.

The storm had top sustained winds of nearly 60 mph as it passed over the Leeward Islands, and was expected to gather strength as it approached Puerto Rico and the U.S. and British Virgin Islands, according to the U.S. National Hurricane Center in Miami. Forecasters said it could become a minimal hurricane later in the week.

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As skies darkened and rain began to fall, people began the familiar ritual of stocking up on gas, food and candles. Tourists at a resort just outside the Antiguan capital said they had no plans to evacuate.

"I am not going to panic," said Maxwell Stevens of New Brunswick, New Jersey. "I will take it in stride."

A tropical storm warning was posted for all the Leewards, including Antigua, Anguilla, St. Kitts and St. Maarten, Puerto Rico and the U.S. and British Virgin Islands, the Hurricane Center said.

At 8 p.m. EDT, the storm was centered about 45 miles northeast of Barbuda, moving west-northwest at 13 mph. It was expected to pass over the northernmost Leewards during the night and skirt the northern edge of Puerto Rico on Wednesday.

The U.S. National Weather Service said Puerto Rico would begin to experience strong gusts of wind and heavy rain Wednesday afternoon. The Leeward Islands and Puerto Rico could receive up to eight inches of rain and could experience flash floods and mudslides, forecasters said.

A hurricane aircraft flew into the storm Tuesday and found that winds had gotten stronger, forecasters said.

In the central Antiguan village of All Saints, people were determined to spend the night celebrating the annual Carnival festival, which locals refer to as "the dance."

"Nothing stops the dance. The weather is good for the dance whether it rains or not," said bar owner Derol Thomas, 38, as he had a pre-party drink with friends Tuesday evening.

Elsewhere in the storm-hardened Caribbean, life went on as normal, though disaster officials urged people to take precautions and told fishermen to haul their boats out of the water.

Long-range forecasts put the storm anywhere from south of Cuba to Florida by late in the weekend.

The first named storm of the 2006 season, Tropical Storm Alberto, swept over Florida in mid-June, then plowed northward along the U.S. coast past the Outer Banks. It was blamed for one drowning.

Last season was the worst in more than 150 years of records. A record number of tropical storms and hurricanes formed, including the devastating Hurricane Katrina.