Fiona takes aim at Puerto Rico, threatening to strengthen into hurricane

Puerto Ricans braced for severe wind and rain as Tropical Storm Fiona bore down amid expectations it would grow into a hurricane before striking the U.S. territory's southern coast on Sunday.

Forecasters said "historic" levels of rain were expected to produce landslides and heavy flooding, with up to 25 inches forecast in isolated areas.

"It's time to take action and be concerned," said Nino Correa, Puerto Rico's emergency management commissioner.