Ernesto has become a Category 1 hurricane Wednesday after hitting Puerto Rico overnight and causing power outages and flooding.
The center of Tropical Storm Ernesto passed 40 miles from San Juan, Puerto Rico, early Wednesday, producing strong winds and heavy rain.
More than 728,000 customers are without power in Puerto Rico, just shy of half the island, according to LUMA, the service provider. The eastern and central areas of the island were the most affected.
LUMA said only the power lines are dead, not the infrastructure that transmits power. It may take 24 to 48 hours to assess the damage before providing a time frame to repair the line.
The main cause of the outage was high winds, which were recorded at 50 mph or more, according to Juan Saca, president and CEO of LUMA Energy.
“In Puerto Rico, the vegetation under the power lines is a major problem. The movement of trees between the lines can easily cause a disturbance,” said Saca.
Despite the challenges, Saca said LUMA is more than ready to restore power.
Additionally, 235,000 customers are without water and more than 400 people are in shelters, according to Puerto Rico officials.
Officials are asking people to leave their homes if absolutely necessary. Many villages are isolated due to river levels and some routes are closed.
Officials are asking people to donate blood because of limited resources. Twenty-three hospitals are using electricity generators and 80 flights have been cancelled.
The storm moved away from Puerto Rico on Wednesday morning with sustained winds of 75 mph.
The highest rainfall total recorded so far was 9.6 inches in Naguabo, Puerto Rico.
All Tropical Storm Warnings have been canceled for Puerto Rico and the Caribbean Islands, but flash flooding is still a problem in Puerto Rico due to heavy rain. The rain is expected to end by Wednesday evening.
On the island of Culebra, east of Puerto Rico, sustained winds of 68 mph were reported with gusts as high as 86 mph. The METAR Observation Station at Roosevelt Roads Naval Station in Puerto Rico reported gusts of 48 mph and gusts of 74 mph.
A tropical storm warning was issued for Puerto Rico and a hurricane watch was in effect for the British Virgin Islands.
On the forecast track, Ernesto will continue to strengthen Thursday through Friday. It could become a Category 3 hurricane by Friday morning with winds up to 115 mph.
Monday night into early Saturday, Ernesto will approach Bermuda as a Category 3 storm at its lowest or a Category 2 hurricane at its highest. Wind and rain are expected.
The East Coast will see high surf and rip currents through this weekend as Ernesto moves parallel to, but also away from, the coast.
President Joe Biden approved a declaration of emergency for Puerto Rico on Tuesday night.
Puerto Rico Governor Pedro Pierluisi has warned residents to stay at home starting Tuesday afternoon, when tropical storm force winds are expected to hit the island. Rainfall amounts could reach 10 inches in some spots.
ABC News’ Jessica Gorman and Josh Hoyos contributed to this report.