A strong 6.4 magnitude earthquake that struck south of Puerto Rico early Tuesday killed at least one person, according to local media, as a series of tremors caused widespread damage across the US territory.
The quake's first reported victim, a 73-year-old resident of the southern city of Ponce, died after a wall fell in his home, El Nuevo Dia newspaper reported.
The island's electric power grid was reported to have collapsed, and houses and other structures, particularly in Guayanilla, home to around 20,000 people, and nearby Guanica were heavily damaged.
Dramatic images shared on social media appeared to show widespread damage in the area.
"The whole island is without power," the director of Puerto Rico Electric Power Authority, Jose Ortiz, told local media.
On social media, people wrote of being shaken awake by the force of the quake.
One woman on Twitter said she had been "wrenched from sleep," adding "everybody is awake & scared all over."
The mayor of Guayanilla told local news channel NotiUno that the town's church had collapsed in the incident and pictures on local media showed the structure crumbled into pieces.
The quake is the most powerful in a series of tremors that have shaken the island since December 28, including a 5.8 magnitude quake on Monday that toppled some structures, caused power outages and small landslides, but no reported casualties.
It also destroyed the popular tourist landmark Punta Ventana, a stone arch that crumbled on the island's southern coast.
- 'Be safe' -
Tuesday's shallow 6.4 magnitude quake struck five miles (eight kilometers) south of the community of Indios and was followed by major aftershocks, the USGS said, revising down its initial reading of 6.6.
The quake hit just off the US territory's southern Caribbean coastline at 4:24 am local time (0824 GMT), with more than a dozen aftershocks in the following hours.
Just ten minutes after the initial quake, a shallow 5.6 magnitude aftershock struck five miles off the southwest coast near Tallaboa, followed by a shallow 5.8 magnitude aftershock at 7:18 am (1118 GMT) one mile south of the community.
Puerto Rico's governor Wanda Vazquez posted on Twitter that the government's security protocols had been activated.
She said government employees were not expected at work, adding: "We want everyone to be safe."
Puerto Rico's port authority said it was inspecting cruise ship and cargo docks following the earthquake.
An alert issued by the Tsunami Warning Center immediately following the earthquake was later cancelled.
Tuesday's quake was the strongest of the series of tremors that have shaken the island since December 28.
Puerto Rico is no stranger to recent natural disaster. The island was devastated in 2017 by Hurricane Maria, a Category 4 storm that shattered the island's already shaky power grid, overwhelmed public services, left many residents without a roof over their heads, and claimed several thousand lives, according to government estimates.