The center of Tropical Storm Ernesto passed within 40 miles from San Juan, Puerto Rico, producing strong winds and heavy rain overnight.

       More than 300,000 customers were without power in Puerto Rico, according to LUMA, a service provider.

       The storm was moving Wednesday morning away from Puerto Rico and was nearing hurricane strength with sustained winds of 70 mph. Hurricane force winds begin at 74 mph.

       On Culebra island, east of Puerto Rico, sustained wind of 68 mph was reported with gust to 86 mph. A METAR Observation Station at the Roosevelt Roads Naval Station in Puerto Rico reported a sustained wind of 48 mph and a gust of 74 mph.

       Tropical storm warnings were issued for Puerto Rico and a hurricane watch was in effect for for British Virgin Islands.

       Puerto Rico Gov. Pedro Pierluisi had warned residents to stay home starting on Tuesday evening, when the tropical storm-force winds are forecast to reach the island. Total rainfall could reach up to 10 inches in some spots.

       A flash-flood warning had been issued for parts of Puerto Rico early Wednesday morning, as several inches of rain already causing flash flooding. Heavy rain and gusty winds will continue in Puerto Rico into the afternoon as Ernesto moves away.

       ABC News' Jessica Gorman contributed to this report.