"Destructive winds and flooding continue over portions of Puerto Rico," the NHC statement reads. Meanwhile, the "center of Maria is approaching the northern coast" of the U.S. commonwealth.
It's 15 miles from Arecibo and 25 miles from San Juan---the capital. It has maximum winds of 140 mph, according to the agency. It's moving northwest at 12 mph.
The Weather Channel said that Maria is doing "major damage" to Puerto Rico.
Buildings trembled as the storm battered San Juan and sent torn off pieces of metal barricades clattering along streets, noted Reuters.
Broken windows, mangled awnings, and gutters dangled haphazardly from buildings or were ripped off entirely. Toilets bubbled noisily and belched foul air as the hurricane rumbled through the city's water and sewage lines.
On its passage through the Caribbean, Maria killed at least one person in the French territory of Guadeloupe and devastated the tiny island nation of Dominica.
"We have not experienced an event of this magnitude in our modern history," Puerto Rico Governor Ricardo Rossello said in a televised message on Tuesday.
"Although it looks like a direct hit with major damage to Puerto Rico is inevitable, I ask for America's prayers," he said, adding the government had set up 500 shelters.
A Hurricane Warning is in effect for: - U.S. Virgin Islands - British Virgin Islands - Puerto Rico, Culebra, and Vieques - Dominican Republic from Cabo Engano to Puerto Plata - Turks and Caicos Islands and the Southeastern Bahamas
A Tropical Storm Warning is in effect for: - Dominican Republic west of Puerto Plata to the northern border of the Dominican Republic and Haiti - Dominican Republic west of Cabo Engano to Punta Palenque