The most powerful hurricane to hit the Caribbean in nearly a decade killed at least 12 people in Grenada (search), damaged 90 percent its homes and destroyed a prison that left criminals running loose, officials said Wednesday. American students took precautions against looters.

Hurricane Ivan (search) killed at least three more people in other countries and was expected to inflict more damage as its 140 mph winds churn toward Jamaica, Cuba and possibly the southern United States.

"We are terribly devastated ... It's beyond imagination," Prime Minister Keith Mitchell (search) told his people and the world — from aboard a British Royal Navy vessel that rushed to the rescue.

Mitchell, whose own home was flattened by Ivan, said 90 percent of homes on the island were damaged and he feared the death toll would rise.

"If you see the country today, it would be a surprise to anyone that we did not have more deaths than it appears at the moment," Mitchell said.

Students at St. George's University, which overlooks the Grenadian capital, hid under mattresses or in bathrooms. "The pipes were whistling, the doors were vibrating, gusts were coming underneath the window," said Sonya Lazarevic, a first-year students from New York.

"It looks like a landslide happened," said another student, Nicole Organ, 21, of Toronto "There are all these colors coming down the mountainside — sheets of metal, pieces of shacks, roofs came off in layers."

She said that the danger didn't end with the winds. Organ said she wandered downtown later and saw bands of machete-wielding men looting a hardware store.

Lazarevic said the mostly American student body was arming with knives, sticks and pepper spray for fear that looters would move into areas near the school.

"We don't feel safe," she told The Associated Press by telephone.

Grenada Police Commissioner Roy Bedaau said every police station in the country had been damaged, hindering efforts to control the looting. He said other Caribbean countries were sending troops to help patrol.

Before slamming Grenada Tuesday evening with winds of more than 120 mph, Ivan pummeled Barbados and St. Vincent, damaging hundreds of homes and cutting utilities. Thousands of people there remained without electricity and water on Wednesday. A 75-year-old woman drowned in Barbados.

In Tobago, officials reported a 32-year-old pregnant woman died Tuesday when a 40-foot palm tree fell into her home, pinning her to her bed.

Details on the extent of the death and destruction in Grenada did not surface until Wednesday because the storm cut all communications with the island of 100,000 people.

U.N. spokesman Fred Eckhard said virtually every major building in St. George's, Grenada's once-quaint capital of English Georgian and French provincial buildings, has suffered structural damage. The United Nations is sending a disaster team, Eckhard said in New York City.

Ivan pulverized concrete homes into piles of rubble and tore away hundreds of the island's landmark red zinc roofs.

In Grenada, emergency workers were having trouble reaching communities beyond roads blocked by uprooted utility poles.

Mitchell confirmed that an unknown number of criminals were on the loose after the country's crumbling and overcrowded 17th century prison, a hilltop fortress in colonial days, was "completely devastated." He said they included some of the 17 people who were jailed for life for killings during a Marxist palace coup in 1983. But he said he didn't know which ones in the group escaped, or if former Deputy Prime Minister Bernard Coard was among them.

Grenada is known for the U.S. invasion that followed the coup, when American officials had determined Grenada's airport was going to become a joint Cuban-Soviet base. Cuba said it was helping build the airport for civilian use. Nineteen Americans died in the fighting.

The storm strengthened even as it hit Grenada, becoming a Category 4, and got even stronger Wednesday, packing sustained winds of 140 mph with higher gusts as it headed across the Caribbean Sea and passed north of the Dutch Caribbean islands of Aruba, Bonaire and Curacao.

In Curacao, the government evacuated 300 residents.

High winds and heavy rains from Ivan flooded parts of Venezuela's north coast, killing a 32-year-old man.

Helicopter charter companies were busy Wednesday ferrying evacuated workers back to offshore oil drilling platforms there.

Ivan is expected to reach Jamaica by Friday morning or Saturday and then aim for Cuba, the U.S. National Hurricane Center in Miami said.

"After Jamaica, it's probably going to hit somewhere in the U.S., unfortunately," meteorologist Jennifer Pralgo of the Hurricane Center said Wednesday. "We're hoping it's not Florida again, but it's taking a fairly similar track to Charley at the moment."

Hurricane Charley killed 27 people in southwest Florida last month and caused an estimated $6.8 billion in insured damage.

Ivan is an "extremely dangerous" storm, said Hugh Cobb of the Hurricane Center, adding this grim warning: "Whoever gets this, it's going to be bad."

Cobb said Ivan is the first Category 4 storm to hit Caribbean islands since Hurricane Luis in 1995.

He said that if Ivan hit Jamaica, it could be more destructive than Hurricane Gilbert, which was only a Category 3 storm when it devastated the island in 1988.

At 8 p.m. EDT, Ivan's eye was about 95 miles north-northeast of Curacao. Hurricane-force winds extended outwards to 70 miles and tropical storm-force winds another 160 miles. Ivan was moving west-northwest at 17 mph.

Haiti posted a hurricane watch for its southwestern peninsula and the Dominican southwest coast was under tropical storm watch. A hurricane warning remained in effect for Aruba, Bonaire and Curacao. Colombia's northeastern Guajira peninsula and Venezuela's north coast were under hurricane watch and tropical storm warning..

Ivan became the fourth major hurricane of the season Sunday, coming hard on the heels of Hurricane Frances, which killed two people in the Bahamas and 14 in Florida and Georgia.