SAN JUAN, Puerto Rico (AP) — A 5.4-magnitude earthquake struck near southern Puerto Rico on Saturday, briefly knocking out power and forcing the relocation of at least 50 families on an island where some people still remain in shelters from previous quakes earlier this year. There were no immediate reports of casualties.

The US Geological Survey said the quake hit at a depth of 5.6 miles (nine kilometres) near the city of Ponce and the towns of Guanica and Guayanilla, where hundreds of homes were destroyed by a quake in early January that killed one person and caused millions of dollars in damage.

The earthquake cracked walls, flung goods off supermarket shelves and caused a second-story balcony to crash in the southern coastal city of Ponce. It occurred amid a two-month lockdown and just hours after the government announced the biggest spike in COVID-19 cases since the first one was reported in March in the U.S. territory.

“This is a crisis on top of another crisis,” said Health Secretary Lorenzo González.

Most of the damage was reported in Ponce, where officials were still going neighbourhood by neighbourhood to assess damage as rescue crews fanned out across the region.

“It’s time to cry if you have to cry,” said Ponce Mayor María Meléndez. “We’re human beings.”

Governor Wanda Vázquez said the 50 families that have to relocated will not be placed in shelters given concerns about the coronavirus contagion. She also urged Puerto Ricans to stay home even if they want to drive to the island’s southern region to help those affected and distribute food as they did earlier this year following the 6.4-magnitude earthquake.

“We’re up against an emergency situation, but we can’t forget that the most lethal one we have in our hands is COVID-19,” she said as she urged people to wear masks and other protective equipment even if they have to evacuate damaged buildings. “If we forget these, the result is going to be worse.”

Meanwhile, in Guánica, Mayor Santos Seda told The Associated Press that no major damage has been reported so far, but noted that between five to 10 people remain in a shelter since the 6.4-magnitude quake that hit in January.

“Thank God everyone is OK,” he said. “The infrastructure is already weak.”

Several aftershocks hit Puerto Rico’s southern region, including a 4.9-magnitude one.

Víctor Huérfano, director of Puerto Rico’s Seismic Network, said in a phone interview that while it’s understandable many people are afraid and surprised by the most recent earthquake, it’s not unusual given the seismic activity that began in the region in late December.

“In the long run, it’s decreasing, but you can have peaks,” he said, adding that he expects strong aftershocks to continue.

Nerves are already frayed in many parts of the island as Puerto Rico continues to recover from Hurricane Maria, a string of strong earthquakes and the coronavirus. Silvestre Alicea, a 67-year-old man who moved back to Puerto Rico from New York upon retiring, lost his home in January’s earthquake and is still living with his sister in Guanica.

“This is unreal,” he said, adding that some neighbours have left the area to stay with relatives elsewhere and that many, including a security guard who worked all night, are now sitting nervously in their balconies. “He hasn’t slept.”

Alicea, however, said he decided to knock down a couple of breadfruits from a nearby tree as the aftershocks continue: “I’m taking it easy. There’s nothing else you can do.”