"Let us band together and unite in the threat of this hurricane," Simpson-Miller said.
Earlier Friday, Dean roared across small eastern Caribbean islands.
In tiny St. Lucia, fierce winds tore corrugated metal roofs from dozens of homes and the pediatric ward of a hospital, whose patients had been evacuated hours earlier. Police spokeswoman Tamara Charles said a 62-year-old man was swept away and drowned when he tried to retrieve a cow from a rain-swollen river.
In Dominica, a woman and her 7-year-old son were killed when a rain-soaked hillside gave way and crushed the home where they were sleeping, said Cecil Shillingford, the national disaster coordinator.
French authorities on the adjacent island of Martinique said a 90-year-old man died of an apparent heart attack during the storm but he was alone and already dead when emergency medical personnel arrived and it was unclear whether Dean was a factor.
People in Martinique, St. Lucia and Dominica mostly stayed indoors Friday while Dean's remnants pounded the islands with heavy rain and authorities tried to assess damage.
Many who did venture out said they were surprised the islands seem to have gotten