PORT OF SPAIN, Trinidad (Reuters) - Powerful and strengthening Hurricane Ivan killed at least three people in Grenada and devastated its capital, St. Georges, as it pounded the tiny islands of the southeastern Caribbean on Tuesday. Ivan, the ninth storm in a busy Atlantic hurricane season, swept south of Barbados and directly over Grenada, brushing past Tobago as it headed into the Caribbean basin far enough south to prompt precautions on the coasts of Colombia and Venezuela. Ivan strengthened into a dangerous category 4 storm on the five-step scale of hurricane intensity, and its 135 mph winds were expected to strengthen as it moved through the Caribbean, the U.S. National Hurricane Center (news - web sites) said. At 11 p.m. EDT, Ivan was about 110 miles west of Grenada. It was racing west at about 18 mph and was expected to turn west-northwest, passing north of the Dutch islands of Aruba, Bonaire and Curacao on Wednesday. Storm warnings were posted for those islands, along with Grenada, St. Vincent and the Grenadines, Colombia's Guajira Peninsula and the entire north coast of Venezuela. As it crossed the fragile Windward Islands on Tuesday, Ivan tore down trees, blew off roofs, knocked out power and forced thousands of people to evacuate coastal areas. It hit hardest in the former British colony of Grenada, a volcanic island of 90,000 people and a major source of nutmeg, cloves and other spices. The storm killed three people in Grenada and destroyed the island's emergency operations center and the home of Prime Minister Dr. Keith Mitchell, the Caribbean Disaster Emergency Response Agency said. Ivan damaged Grenada's main hospital and several of its hurricane shelters, forcing some of the 1,000 people who sought refuge there to move to other shelters. 'INCALCULABLE DAMAGE' "The capital of St. Georges suffered incalculable damage," the regional intergovernment agency said. Regional aid groups and utility crews were being sent to Grenada and a British Navy ship was readied to provide aid, the agency said. In Barbados, a former British colony of 278,000, Ivan felled trees and power lines, hurled debris around and damaged 220 houses. It blew the roof off the landmark Atlantis hotel, built in 1884 on the seafront at St. Joseph, and damaged the roof of a new hangar near the airport housing a preserved Concorde jet. Most of Barbados was without electricity. "I'm feeling glad that it didn't hit us in full," said Shellie Welch of Christchurch in the south of Barbados, who sat out the storm at home with her two children. "I'm just imagining what if it did, because the houses here aren't built all that strong." On the resort isle of Tobago, the storm ripped off dozens of roofs in 14 villages and knocked out power. The twin-island nation of Trinidad and Tobago has a population of 1.1 million and is the Caribbean's top oil producer. TRINIDAD LARGELY SPARED Trinidad was largely spared, but its energy companies evacuated workers from offshore oil platforms and halted production before the storm hit. Atlantic LNG stopped export shipments as the storm approached Trinidad, which is the largest liquefied natural gas supplier to the United States. In St. Lucia and St. Vincent and the Grenadines, residents packed into shelters, fearing their houses might not withstand the heavy rain and winds. St. Vincent and the Grenadines Prime Minister Dr. Ralph Gonsalves said the storm tore the roof off a hospital and damaged several houses on Union Island. "The sea has come in and removed a couple of houses. Apparently there were waves of up to 20 feet high so that has been very terrible," Gonsalves told a Trinidad television station. Ivan spun off squalls that battered Venezuela's coastline. Officials in northeastern Sucre State and nearby Margarita Island moved residents away from risky coastal areas, restricted air and sea traffic and closed some airports and harbors, Civil Protection Service chief Antonio Rivero said. The hurricane center's long-range forecast, which has a large margin of error, put the storm over Jamaica on Friday and southwestern Cuba on Sunday. SOURCE: YAHOO.COM/REUTERS