NEW YORK (Reuters) - Utility crews from the U.S. mainland were scrambling to Puerto Rico on Thursday after Hurricane Maria left nearly the entire U.S. territory, and many of its Caribbean neighbors, without power, according to officials. The Puerto Rico Electric Power Authority (PREPA) reported almost 100 percent of its 1.5 million customers were without power as of late Wednesday, the U.S. Department of Energy said in an update on the hurricane s impact on Thursday, after Maria s winds snapped trees and utility polls.  Puerto Rico Governor Ricardo Rossello told CNN PREPA was so severely hit that it could be months before electricity is restored to all those customers. President Donald Trump said on Thursday that Hurricane Maria  totally obliterated  the U.S. island territory of Puerto Rico with its electrical grid destroyed. In the U.S. Virgin islands, the majority of the 25,000 customers on St. Croix were also reported to be without power, the DOE report added. Energy support crews have been deployed to St. Thomas and St. Croix in support of Federal Emergency Management Agency (FEMA) teams there, and others are prepared to deploy to Puerto Rico as soon as conditions permit, the DOE said. The American Public Power Association said it was also bringing in utility and contractor crews from parts of the U.S. mainland to help with recovery efforts.  At least one support team is already in Puerto Rico, said Mike Hyland, senior vice president, engineering services at the association, in a phone interview.  They ve been in San Juan since Maria passed and I believe they re going today to St. Thomas. ... Right now our mission is to get the lights back on,  he said, adding that there were limited flights and barges serving the islands.  The power outages have forced critical facilities, like hospitals, to rely on generators, and raised concerns about potential fuel shortages as some gas stations may not have backup power.  The fuel is there, you just can t pump it,  said Patrick DeHaan, petroleum analyst at Gasbuddy.  Maria killed at least 10 people as it raged through the Caribbean, the second major hurricane to do so this month. It packed winds of up to 155 mph (250 kph), when it made landfall on Puerto Rico on Wednesday as the strongest storm to hit the U.S. territory in nearly 90 years. Maria s devastation comes just as Puerto Rico, which is facing the largest municipal debt crisis in U.S. history, and PREPA, which is bankrupt, were recovering from Hurricane Irma, which grazed the island, knocking out power to two-thirds of the residents. Petroleum supplies just under half of the island s electricity, and natural gas supplies nearly one-third, according to federal government data.  In recent years, high world petroleum prices have driven typical Puerto Rican power prices as high as three times those in the U.S. mainland. Maria, which could strengthen somewhat over the next day or so, was forecast to move north in the Atlantic Ocean over the weekend, the NHC said. 