Ernesto becomes hurricane after leaving 714,000 without power in Puerto Rico

Ernesto has become a Category 1 hurricane Wednesday after hitting Puerto Rico overnight and leaving power outages and flooding in its wake.

The center of then-Tropical Storm Ernesto passed within 40 miles of San Juan, Puerto Rico, early Wednesday, producing strong winds and heavy rain.

More than 714,000 customers are without power in Puerto Rico, just shy of half the island, according to LUMA, a service provider. The island's eastern and central regions are the most impacted.

LUMA said only power lines are down, not the infrastructure that delivers power. It will need 24 to 48 hours to assess damage before providing any time frame for repairing the lines.

Additionally, 235,000 customers are without water and over 400 people are in shelters, according to Puerto Rican officials.

Officials are asking people to leave their homes only if absolutely necessary. Many villages are completely isolated because of the river levels and multiple routes are closed.

Officials asked people to donate blood due to low resources. Twenty-three hospitals are using electric generators and 80 flights have been canceled.

The storm was moving away from Puerto Rico on Wednesday morning with hurricane-force winds of 75 mph.

The highest rainfall total recorded so far is 9.6 inches in Naguabo, Puerto Rico.

More rain is possible Wednesday morning and into early afternoon before the storm moves out of Puerto Rico.

On Culebra island, east of Puerto Rico, sustained winds of 68 mph were reported with a gust up to 86 mph. A METAR Observation Station at the Roosevelt Roads Naval Station in Puerto Rico reported sustained winds 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 the British Virgin Islands.

President Joe Biden approved an emergency declaration for Puerto Rico on Tuesday night.

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 was issued for parts of Puerto Rico early Wednesday morning, as several inches of rain already caused flooding. Heavy rain and gusty winds will continue in Puerto Rico into the afternoon as Ernesto moves away from the island.

ABC News' Jessica Gorman and Josh Hoyos contributed to this report.