A 6.4 magnitude earthquake, followed by several aftershocks, has struck off the southern coast of the US territory of Puerto Rico, killing at least one person and injuring eight others while collapsing houses, destroying a popular tourist landmark and leaving the island without power, officials said.

The quake hit five miles south of the island's southern coast at 4:24am (8:24 GMT), according to the United States Geological Survey (USGS).

More:

Just 10 minutes later, a shallow 5.6 magnitude aftershock struck five miles off the southwest coast near Tallaboa, followed by a shallow 5.8 magnitude aftershock at 7:18am (11:18 GMT) one mile south of the community.

The events prompted Puerto Rico's governor Wanda Vazquez to declare a state of emergency and activate the national guard to deal with the disaster's aftermath, El Neuvo Dia newspaper reported.

The quakes cut power to the island as power plants shut down to protect themselves. Authorities said two plants suffered light damage and they expected power to be restored later on Tuesday.

"The whole island is without power," the director of Puerto Rico Electric Power Authority, Jose Ortiz, told local media.

A shop was damaged after an earthquake in Guanica [Ricardo Ortiz/Reuters]

Before declaring a state of emergency, 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."

Teacher Rey Gonzalez told The Associated Press news agency that his uncle was killed when a wall collapsed on him at the home they shared in the city of Ponce. He said 73-year-old Nelson Martínez was disabled and that he and his father cared for him.

Eight other people were injured in Ponce, near the epicentre of the quake, Mayor Mayita Melendez told WAPA television. Hundreds of people sat in the streets of the city, some cooking food on barbecue grills, afraid to return home for fear of structural damage and aftershocks.

La suspensión de labores por el día de hoy en el sector público no incluye a los empleados públicos de primera respuesta. Todos ellos se reportan a sus áreas como de costumbre. — Wanda Vázquez Garced (@wandavazquezg) January 7, 2020

The island's main airport was operating normally, using generator power, according to authorities.

Tuesday's earthquake was the strongest of a series of tremors that have shaken the island since December 28, topping Monday's 5.8 magnitude quake. The 10-day series of earthquakes have been caused by the grinding of tectonic plates along three faults beneath southern Puerto Rico, according to seismologists, who say it is impossible to predict when the activity will stop or whether it will get stronger.

An alert issued by the Tsunami Warning Center immediately following the earthquake on Tuesday was later cancelled.

Homes, churches and tourist attractions destroyed

Residents of affected areas said they were shaken awake by the force of the earthquake, with many taking to social media to describe the harrowing experience.

Albert Rodríguez, who is from the southwest town of Guanica, told the Associated Press that tsunami sirens went off before officials cancelled the alert.

He added there was widespread damage in his neighbourhood.

“The road is cracked in the middle and it lifted up,” he said.

Dramatic images on social media appeared to show widespread damage in the town of Guayanilla, home to about 20,000 people, as well as nearby Guanica. Some on social media reported that hospitals and schools were also damaged.

My family in #PuertoRico woke up to this scene on January 7th, 2020 #PuertoRicoEarthquake Take a look at school in Guanica, PR pic.twitter.com/NSOSyqPISy — Eddie M. Guerra (@eddiemguerra) January 7, 2020

The mayor of Guayanilla told local news channel NotiUno that the town's church had collapsed in the incident.

The popular tourist landmark Punta Ventana, a stone arch in Guayanilla on island's southern coast, also crumbled during the earthquake.

Popular tourist landmark Punta Ventana was destroyed after a 5.8-magnitude earthquake in Guayanilla [Ricardo Arduengo/AFP]

The earthquakes are the most recent natural event to threaten Puerto Rico. In 2017, Hurricane Maria, a Category 4 storm, shattered the island's already shaky power grid, overwhelmed public services, left many residents without a roof over their heads, and killed several thousand people according to government estimates.

One of the largest and most damaging earthquakes to hit Puerto Rico occurred in October 1918, when a magnitude 7.3 quake struck near the island’s northwest coast, unleashing a tsunami and killing 116 people.