Hurricane Maria has slammed into Puerto Rico as the strongest storm to hit the US territory in nearly 90 years, downing power to most of the island, flooding some areas and ripping windows out in the capital San Juan.
Maria, the second major hurricane to roar through the Caribbean this month, made landfall near Yabucoa, on the southwest of the island of 3.4 million people. Thousands of people were seeking safety in shelters.
Carrying winds of 220km/h, driving high storm surges and drenching rains, Maria's eye was located about 40km west of San Juan shortly before 11am local time, the US National Hurricane Center said.
Broken windows, mangled awnings and gutters dangled haphazardly from buildings in San Juan or were ripped off entirely. Toilets bubbled noisily and belched foul air as the hurricane rumbled through the city's water and sewage lines.
Up to 90 per cent of the island was without electricity, El Nuevo Dia newspaper quoted Governor Ricardo Rossello as saying.
In the southcoast city of Guayama, west of where Maria blew ashore, storm waters turned streets into fast-running rivers carrying wind-downed debris.
"God is with us; we are stronger than any hurricane," Mr Rossello said in a Twitter message on Wednesday. "Together we will rise again."
Maria was expected to dump as much as 66cm of rain on parts of Puerto Rico, the NHC said. Storm surges, when hurricanes push ocean water dangerously over normal levels, could be up to 2.7 metres. The heavy rainfall could cause life-threatening flash floods and mudslides, it added.
Before hitting Puerto Rico, Maria ripped off roofs and downed trees as it passed west of St Croix, home to about half of the US Virgin Islands' 103,000 residents, as a rare Category 5 storm, the top of the five-step Saffir-Simpson scale.
About 65 to 70 per cent of the buildings on St Croix were damaged by the storm, said Holland Redfield, who served six terms in the US Virgin Islands senate.
In Guadeloupe, at least two people were killed, according to France's minister for overseas territories. Many roads were blocked and about 80,000 people, or 40 per cent of the population, were without power, the overseas territories ministry said in a statement.
In the largest city, Point-a-Pitre, there was flooding of more than a metre in parts of the city, access to the port was blocked and a hospital was damaged, it said.
Maria was on a track to pass just north of the northeast coast of the Dominican Republic on Wednesday night and Thursday, the US National Hurricane Center said. So far, it did not look likely to threaten the continental US.