The quake hit close to the town of Tallaboa on the island’s south coast, at 4:24 a.m. local time (03:24a.m EST) at a depth of 10 kilometers, USGS said.
The earthquake’s magnitude was initially reported as 6.6, but was revised down first to 6.5, then 6.4.
At least one one is known to have been killed in the quake. The Associated Press reported that the victim was killed when a wall collapsed on him at his home. Eight people are were also injured in the city of Ponce, near the epicenter of the quake, Mayor Mayita Meléndez told WAPA television, according to the AP.
The Electric Power Authority reported an island-wide power outage, saying on Twitter that power plants had activated their protection mechanisms and gone out of service.
Authorities said damage had been reported at the Costa Sur power station, and they were evaluating the power infrastructure and urged residents to remain calm. The Electric Power Authority said it hoped it would be able to bring the power back online later Tuesday.
The U.S. Coast Guard is conducting overflight assessments to identify any potential signs of pollution in the water or damage to the port infrastructure and navigable waterways.
All ports in Puerto Rico and the U.S. Virgin Islands remain open until further notice, the U.S. Coast Guard said in a news release.
Albert Rodríguez, who is from the southwest town of Guánica told the Associated Press there is widespread damage in his neighborhood.
“The road is cracked in the middle and it lifted up,” he said.
Videos posted on social media showed damage to buildings, including a church in the town of Guayanilla with a steeple that had collapsed.
Puerto Rico Gov. Wanda Vázquez Garced announced on Twitter that public sector institutions would be closed for the day so that workers “can be with their families, implementing their emergency plans.”
In addition to the magnitude 6.5 quake, at least seven other earthquakes were recorded by the USGS as striking Puerto Rico in the early hours of Tuesday. Some of the subsequent quakes measured up to magnitude 5.6.
There is currently no tsunami warning in effect, according to the National Tsunami Warning Center.
The quake comes one day after a 5.8 quake hit the U.S. territory’s southern region, which has seen a string of quakes in recent days.
Monday’s earthquake collapsed five homes and damaged many other buildings and also caused rock slides and power outages, according to the Associated Press..