The largest of the quakes in the U.S. territory registered at magnitude 6.4, the most powerful to hit the Caribbean island in 102 years.
Puerto Rico Governor Wanda Vazquez declared a state of emergency Tuesday after a series of earthquakes killed at least one person, toppled buildings and knocked out power to nearly the whole island of more than three million people.
With two large power plants shut down, drinking water was cut off to at least 300,000 customers, Vazquez told a news conference. She said she did not know when power would be restored on the island, still recovering from a pair of devastating 2017 hurricanes.
The island's electricity authority said it hoped to re-establish services during the night in the metropolitan area of the capital, San Juan, home to about 2.3 million people.
At least 346 people were left homeless, officials said, after homes were flattened, mostly in the south of the island. Many damaged buildings sat next to piles of rubble.
Bottled water, batteries and flashlights ran low at San Juan supermarkets and ice was scarce as residents tried to stop food rotting in refrigerators, said resident Luis Borri, 31.
"Water is running out, people are grabbing like 10 boxes," said Borri, who recharged his cellphone at San Juan's international airport where he works and where backup generators allowed normal services to continue.
The island's emergency declaration will facilitate federal financial aid. Vazquez said she had been in contact with the Federal Emergency Management Agency (FEMA). Several members of Congress, including Florida's two U.S. senators and Puerto Rico's non-voting member of the House of Representatives, appealed to U.S. President Donald Trump for aid.
The island has been rocked by hundreds of quakes since Dec. 28, including 10 of magnitude four or greater, the U.S. Geological Survey said. A 5.8-magnitude quake on Monday damaged some homes on the southern coast.
Powerful quakes are rare in Puerto Rico. In 1918, a 7.3 magnitude quake and tsunami killed 116 people, according to the island's seismology office Red Sismica.
Hurricanes Irma and Maria in 2017 killed about 3,000 people and destroyed a significant amount of infrastructure.
One of Tuesday's quakes triggered an automatic shutdown of electricity across the island as a safety measure and a later, more powerful quake damaged power plants in the southern part of the island, Vazquez said.
Puerto Rico was producing 53 megawatts of electricity, when demand was close to 2,000 megawatts, but hoped to add an extra 200 megawatts soon, Angel Figueroa, president of the electricity workers' union UTIER, said on Twitter.
The governor said a 73-year-old man died after a wall fell on him, but it was too soon to offer a full assessment of damage or injuries.