After crossing St. Croix, Maria will head toward the Virgin Islands and Puerto Rico on Tuesday night and Wednesday as "an extremely unsafe Category 4 or 5 hurricane", the National Hurricane Center said.
It's been less than two weeks since Hurricane Irma slammed into the Eastern Caribbean as a Category 4 storm, devastating numerous tiny islands in its path before barreling into Florida.
She added: "We are under no illusions about the possible impact of Hurricane Maria and are taking every measure possible to prepare communities which have already been devastated by Hurricane Irma".
Forecasts show Hurricane Maria approaching the islands Tuesday night and Wednesday.
"Initial reports are of widespread devastation", Prime Minister Roosevelt Skerrit posted on his Facebook page early Tuesday. Central and southern Leeward Islands could see as much as 20 inches of rain, according to the National Hurricane Center.
"It is too early to speak of the condition of the air and seaports, but I suspect both will be inoperable for a few days".
"This storm promises to be catastrophic for our island", he said.More news: 'Get out!' Julia Louis-Dreyfus wins record 6th consecutive Emmy for 'Veep'
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This article has been updated with more details about Hurricane Maria.
That's a sign of an extremely strong hurricane likely to get even mightier, said University of Miami hurricane researcher Brian McNoldy.
The U.S. National Hurricane Center said Maria had maximum sustained winds of 160 miles per hour late Monday.
Maria made landfall on Dominica around 9:15 p.m. local time with estimated winds of 160 miles per hour, radar data from Martinique and Air Force Reserve Hurricane Hunter aircraft indicated, according to the National Hurricane Center. "All of Puerto Rico will experience hurricane force winds".
Officials in Dominica closed schools and government offices on Monday and urged people to evacuate and seek shelters.
A Marine Corps MV-22B Osprey takes off from the USS Kearsarge aircraft carrier as United States military continues to evacuate personnel from the U.S. Virgin Islands in advance of Hurricane Maria, in the Caribbean Sea near the islands. In Puerto Rico, residents were also warned of the upcoming storm, which is expected to arrive in the area on Wednesday as a category 3. The island avoided a direct hit from that storm, but Irma's powerful storm surge and winds still caused many residents to lose power.