Hurricane Dean has strengthened to a category four "major" storm, pounding the eastern Caribbean with winds in excess of 215km/h (130 mph).
The US National Hurricane Center upgraded the storm as it moved towards Mexico, killing a man in St Lucia. It could become category five, it said.
The first hurricane of the Atlantic season caused landslides and ripped off roofs in St Lucia and Martinique.
In Texas, five people died in flash floods caused by Tropical Storm Erin.
Rescuers are searching for two people missing in the thunderstorms. Central and southern Texas are braced for more rain on Friday.
"The ground's already saturated, then with the amount of rain we got today it's just running off and causing flash flooding, so if we get additional rain it will be a major concern for us," said a regional emergency co-ordinator, Orlando Hernandez.
US forecasters have warned that Hurricane Dean could reach the Gulf of Mexico by Wednesday, threatening the US-Mexico border region.
Workers on oil and natural gas platforms in the Gulf of Mexico were evacuated to safety on Friday, officials said.
Meanwhile, Nasa is monitoring the hurricane.
More heavy rain is forecast for central and southern Texas
It says if the storm veers towards Houston, it may order space shuttle Endeavour, due to land back on Earth on Wednesday, to either return early or extend its stay at the International Space Station.
At 1745 GMT, the hurricane's centre was located about 280km (175 miles) west of Martinique, moving west at about 35km/h (22mph).
Residents on the island of Martinique reported landslides and flooding, as the eye of the storm passed through the narrow St Lucia Channel.
"In one village, telephone and power lines are down, they're strewn all over the road, trees are uprooted and are blocking the roads," Heraldine Rock, a former MP, told Reuters.
"In another village, a landslide has been reported, cutting off any access to the airport."
A caller to Radio Martinique said: "There is water in my house. There is water in my room. I don't know what to do. Everything is shaking, shaking, shaking. It's truly catastrophic."
Earlier, the storm claimed its first victim on the island of St Lucia, where a 62-year-old man drowned after being swept away in a swollen river while trying to save a cow.
Many roads are blocked by debris and uprooted trees
State radio reported flooding in the capital, Castries.
Jamaica's prime minister called an emergency meeting of the country's disaster preparedness committee in anticipation of the hurricane, which could hit over the weekend.
Tropical storm warnings are in place for the British and US Virgin Islands, Puerto Rico, Antigua and Barbuda, Montserrat, St Kitts and Nevis, Anguilla and St Maarten and Grenada.
No substantial damage was reported in Dominica, where the government had cancelled leave for the emergency services.