Waves as high as two storeys, heavy rains and driving winds announced the approach of Hurricane Ivan Friday night in Jamaica as trees were ripped out of the ground and roads were torn up by flooding. Ivan was forecast to make landfall late Friday or early Saturday in western Jamaica as the strongest storm the island has seen in 16 years. It strengthened as it neared Jamaica, blasting maximum sustained winds of 240 kilometers per hour, making it a category 4 storm on the five-level Saffir-Simpson scale. "Winds have ripped out banana and coconut trees and most of the agricultural sector has been severely impacted," Sophia Mitchell, a spokeswoman at Jamaica's Office of Disaster Preparedness and Emergency Management, told the Bloomberg news service ahead of landfall. Prime Minister Percival Patterson declared a state of emergency Friday, and his government ordered 500,000 people, nearly a fifth of the population, to evacuate low-lying areas, but by Friday night, about 5,000 had retreated to emergency shelters. Many others refused to leave their houses because they were afraid of looting although police were patrolling the streets in a bid to prevent thievery. Ivan already had left at least 33 people dead - 24 in Grenada, four in the Dominican Republic, two in Venezuela, and one each in Colombia, Tobago and Barbados. Its effect in Grenada was catastrophic with 90 per cent of the island's buildings damaged. --more 1457 Local Time 1157 GMT