"Oh my God, I can't describe it," said Janice McKinney, who was running a shelter for about 50 people in a boarded-up church on Great Inagua Island in the south-eastern Bahamas.
The pastor was leading the congregation in prayer as the wind howled outside, she told the Associated Press news agency.
Thousands of tourists and residents left the normally tranquil Turks and Caicos islands as the storm closed in, but hundreds more sought refuge there - some in shelters, others in closets and under stairwells, AP reported.
"[People were] just holding on for life," Turks and Caicos Prime Minister Michael Misick was quoted as saying.
"They got hit really, really bad. A lot of people have lost their houses, and we will have to see what we can do to accommodate," he said.
The British Red Cross hopes to provide relief to people in the Turks and Caicos islands - a UK overseas territory - and in the wider region, by providing a supply plane, more shelters, hygiene kits, food, clothing and bedding.
Relief operations manager Pete Garrett told the BBC the extent of the damage had not yet been established but the existing shelters had been crammed full of people overnight.
Forecasters say Ike could unleash up to 12in (30cm) of rain in its wake, including on Haiti, where earlier storms left at least 600 dead.
The battered country was hit with fresh downpours as Ike's outer rain band passed over its north-west coast.
BBC Weather tracks Hurricane Ike
Dozens of people were found dead on Sunday in flooded Cabaret, a town north of the capital, Port-au-Prince.
Meanwhile, the only bridge giving access to the flooded Haitian city of Gonaives, which is still reeling from other recent storms, collapsed.
The UN children's charity Unicef says some 650,000 Haitians have been affected by flooding caused by Tropical Storm Hanna last week, while more bad weather will further hamper the aid effort there.
Forecasters say Ike could strengthen on its way to Cuba, threatening to devastate the island's sugar cane fields and putting the crumbling colonial buildings of the capital, Havana, at risk.
In Havana, residents have been stocking up on petrol, candles and canned food, after a television weather presenter said "almost the entire country is in the danger zone", AP reports.
On its current track the storm could threaten the islands of the Florida Keys by Tuesday. Some residents have received evacuation orders.
Emergency management director Craig Fugate, urged them to move soon, or they "may find the escape route blocked by a hurricane".
The destruction in Haiti has been described as catastrophic.
Hurricane Ike has brought fresh misery to Haiti
Police said 500 people were confirmed dead from recent Tropical Storm Hanna but that others are still missing and the number could rise.
Aid workers say people's spirits are running low after the successive storms.
"Food supplies and water are scarce and the price of the food that's left is rising," said Parnell Denis from Oxfam in Gonaives, the port city hardest hit by Hanna, where floodwaters reached nearly 5m (16ft) high.
Hanna struck in the wake of Hurricane Gustav and Tropical Storm Fay two weeks ago, which left about 120 people dead in Haiti.
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.