Heavy rains were forecast to start late Friday in Antigua and Barbuda, the U.S. and British Virgin Islands and southern and eastern Puerto Rico.

SAN JUAN, Puerto Rico — Hurricane Erin exploded in strength to a Category 5 storm in the Caribbean on Saturday, rapidly powering up from a tropical storm in a single day, the National Hurricane Center said.

Erin has strengthened into a hurricane as it approaches Puerto Rico and the Virgin Islands, bringing heavy rains that could cause flooding and landslides.