U.S. forecasters downgraded Hanna from a hurricane to a tropical storm as it made its way through the Bahamas on Tuesday morning, even as the storm caused heavy flooding in Haiti that killed 10 people.

The 10 bodies were found Tuesday in Gonaives along Haiti's western coast, said Marie Alta Jean-Baptiste, the country's civil protection director.

"The situation is as bad as it can be," said Vadre Louis, a UN investigator based in Gonaives.

"The wind is ripping up trees. Houses are flooded with water. Cars can't drive on the street. You can't rescue anyone wherever they may be."

As of 2 p.m. ET, maximum sustained winds from the storm had fallen to 110 km/h from the 130 km/h speed they were measured at earlier Tuesday, the U.S. National Hurricane Center said, warning that the system may pick up strength and become a hurricane again later in the day.

The storm system is moving erratically and slowly, inching along at four km/h, but is expected to move northwest into the central Bahamas over Tuesday night and into Wednesday.

Hanna's slow and irregular movement is posing problems for U.S. forecasters trying to determine where the storm will hit once it makes landfall in the United States.

"Right now, the uncertainty is such that it could hit anywhere from Miami to the Outer Banks of North Carolina," said Jessica Schauer Clark, a meteorologist at the U.S. National Hurricane Center. "So people really need to keep an eye on it."

Forecasters said it could hit the U.S. coast by Friday or Saturday.

The Turks and Caicos Islands, Inagua and Crooked Island in the Bahamas, and Haiti were already hit by pounding surf and heavy rainfall caused by Hanna on Monday.

There were no immediate reports of injuries or major damage in the Bahamas or the Turks and Caicos Islands, but emergency teams were standing by and would begin assessing the situation once the storm cleared, said Stephen Russell, interim director of the Bahamas National Emergency Management Agency.

Rain brought by Hanna caused flooding that killed a man from Colombia and left a Brazilian woman missing on Monday in Puerto Rico. The two were students at the University of Puerto Rico on a trip to the island's east.

Hanna's winds and rain reached all the way to Haiti, where thousands remain homeless in the wake of Gustav, which was downgraded to a tropical depression as it moved over Louisiana early Tuesday.

Newly formed tropical storm Ike, meanwhile, was cruising westward across the Atlantic and is projected to near the storm-weary Bahamas by Sunday. It had winds of 85 km/h as of 5 a.m. ET on Tuesday and is expected to grow stronger.

Another storm looms

In a development that could compound the effects of a busy week in the tropical Atlantic, yet another tropical storm has formed in the ocean.

The U.S. National Hurricane Center in Miami says Josephine — the 10th named storm of the Atlantic hurricane season — is about 270 kilometres southeast of the Cape Verde Islands.

Josephine has sustained winds near 65 km/h and is moving west at about 25 km/h.

Forecasters said it could gain hurricane strength with sustained winds of at least 119 km/h by Wednesday or Thursday.

With files from the Associated Press