A 5.2 magnitude earthquake cracked walls and brought down power lines in Puerto Rico on Friday as the Caribbean island was recovering from its worst quake in over a century on Tuesday.
The latest quake took place at 6.26pm, local time, with its epicentre around 4 km south of Indios on the southern coast, the US Geological Service reported.
The quake was felt in the capital San Juan and to the west authorities closed a road bridge near Caguas that was in danger of collapsing after cracks appeared.
Shaken residents in the south said it was the strongest they had felt since Tuesday's 6.4 magnitude earthquake, which killed at least one person, destroyed or damaged about 300 homes and knocked out power across the island.
"Please no more," tweeted Nick Silva, showing a crack in his wall.
The island is in the process of restoring power to its nearly three million residents after Tuesday's earthquake severely damaged its largest generating plant, Costa Sur.
The lights stayed on in San Juan after Friday's quake, residents said, but there were reports on Twitter of new blackouts in the west of the island.
Puerto Rico Governor Wanda Vazquez and US Senator Rick Scott on Friday toured the Costa Sur plant in Guayanilla and spoke to US President Donald Trump by telephone.
They said Trump pledged his support for Puerto Rico after he earlier in the week approved an emergency declaration to mobilize resources for recovery efforts.
"I will work my tail off to make sure all the federal resources that can be available will be available," Scott told reporters.
In the aftermath of Tuesday's earthquake only half of the Caribbean island had power. Scott said over 6000 people were in emergency shelters, many of them fearful their own homes could collapse during another major earthquake.
Vazquez on Thursday said that without another major earthquake she expected power to be fully restored across the island by Monday.
Authorities have promised that the earthquake blackouts will not be a repeat of the lengthy power outages the island suffered following back-to-back hurricanes in 2017.
The earthquake has added to Puerto Rico's woes as it is still recovering from Hurricanes Maria and Irma in 2017 which killed around 3000 people, and goes through a bankruptcy process.