All of Puerto Rico is without power after Hurricane Maria slammed into the U.S. territory on Wednesday morning as a Category 4 storm, bringing vicious winds, storm surge and rain to areas across the island before losing strength by nightfall.

The storm weakened to a Category 2 late Wednesday, but was upgraded to a Category 3 early Thursday as it pounded the Dominican Republic. The storm is expected to next take aim at Turks and Caicos, which were devastated by Hurricane Irma earlier this month.

Widespread outages were also reported on the U.S. Virgin Islands, which also took a beating on Wednesday, Federal Emergency Management Agency director Brock Long said.

Both territories are basically without power and will be so for a very long time, he told Fox Business. They both have very fragile power systems.

Ongoing storm conditions have prevented FEMA workers from fully assessing how Maria has affected the people on the islands, he continued.

We dont have a good handle on the search and rescue at this point from the standpoint of fatalities or people trapped.

In Puerto Rico, catastrophic flash flooding continued into Wednesday evening across the island, the National Hurricane Center said in its latest advisory.