ROSEAU, Dominica (AP) — Leaders across much of the Caribbean closed schools and government offices Wednesday as Tropical Storm Isaac churned toward the region. The US military postponed hearings for September 11 prisoners ahead of a storm that could sweep across Cuba and perhaps eventually menace Florida as a hurricane.

The storm was 25 miles (40 kilometres) south-southeast of Guadeloupe late Wednesday afternoon, with maximum sustained winds of 45 mph (75 kph and was expected to become a hurricane by Thursday night or Friday, the US National Hurricane Center said.

Dominica Prime Minister Roosevelt Skerrit urged people to stay home from work Wednesday.

Military authorities at the US base in Guantanamo Bay, Cuba, canceled several days of pretrial hearings in the case of five prisoners charged in the September 11 attacks. They also planned to evacuate about 200 people, including legal teams and relatives of September 11 victims.

In Puerto Rico, Governor Luis Fortuno declared a state of emergency and activated the National Guard. He also canceled classes and closed government agencies. The storm was expected to pass just south of Puerto Rico on Thursday.

The US Virgin Islands commissioner of public works, Darryl Smalls, said crews distributed sandbags to residents in St Croix, where schools and government offices were ordered not to open Thursday. St. Kitts announced similar closures for Wednesday.

In Martinique, officials warned of swollen rivers and flooding. Meteorologist Jean-Noel Degrace said at least three inches (eight centimetres) of rain fell Wednesday morning. The leader of Martinique, Laurent Prevost, urged people in low-lying areas to evacuate.

In the Dominican Republic, authorities banned boats from entering its waters and warned of heavy rains from Thursday through Saturday.

The storm's centre was expected to move over the Leeward Islands on Wednesday evening, and forecasters said it was likely to hit the Dominican Republic and Haiti as a hurricane Friday. It was predicted to move on to Cuba as a tropical storm.