Hurricane Fiona strengthened to a Category 3 storm on Tuesday after slamming into Puerto Rico and the Dominican Republic.
The National Hurricane Center said Fiona could grow more powerful as it approaches Bermuda later in the week.
Rising global temperatures contribute to more intense storms, according to a growing body of research.
Hurricane Fiona tore through Puerto Rico as a Category 1 storm on Sunday, cutting power to the island's 3 million residents and leaving most of them without water.
"We woke up without water. Most people don't have electricity, but thankfully I have solar panels. There's long lines for gas to power generators," Ruth Santiago, an environmental lawyer and advocate who lives in the town of Salinas in southern Puerto Rico, told Insider in Spanish on Tuesday morning.
But by Tuesday, after it ripped through the Dominican Republic, Fiona strengthened to a Category 3 with sustained winds of 115 miles per hour. That makes it the first major hurricane of the 2022 season.
It's expected to bring "hurricane conditions" to Turks and Caicos and portions of the Bahamas, according to the National Hurricane Center. The center said it could strengthen further into a Category 4 hurricane as it approaches Bermuda later in the week.
In Puerto Rico, the storm unleashed severe flash flooding, with one weather station reporting more than 2 feet of rain in 24 hours. Officials said more than 900 people were rescued across the island and at least 1,300 people spent the night in shelters, according to The Associated Press."There's water all over the place," Santiago said, adding that one of the offices she works out of is flooded, after the roof collapsed.
"Localized additional flash and urban flooding is possible in southern portions of Puerto Rico," the National Weather Service warned, adding that another 1 to 4 inches of rain will fall over much of Puerto Rico into Wednesday morning.
FEMA officials said the agency is currently in the reponse phase. "We are really stressing all impacted individuals look into the local emergency managers and focus on safety, and make sure that they watch out for floodwaters," Keith Turi, FEMA's assistant administrator for recovery, told reporters on Tuesday afternoon. "This is still very much a life saving mission at this point, and that's our focus."
"We'll be sending hundreds of additional staff over the next couple of days and we continue to assess the need," Turi added. "We've got a few 100 responders that are already on the ground" in Puerto Rico.
At one point on Sunday, the entire island was without power. According to LUMA Energy - the private company that operates power transmission and distribution in Puerto Rico - power had been restored to more than 286,000 customers as of 6:30 a.m. ET Tuesday. The company said it could take days to fully restore service.
"I hope that the government - both the Puerto Rican government and FEMA - incorporate solar panels so folks, like me, can have electricity in these kinds of disasters," Santiago said.
Jose Luis German Mejia, an emergency management official, told CNN, that more than one million people in the country are without running water after the storm knocked 59 aqueducts out of service.
On Tuesday, FEMA officials told reporters there were four confirmed fatalities following the storm. CNN reported a 58-year-old man was washed away by La Plata River behind his home in Comerío. In a separate incident, firefighters in the city of Arecibo said one man died from burn wounds after attempting to fill his generator with gasoline.
The storm killed at least one man in Guadeloupe, and one person died in the Dominican Republic after being hit by a falling tree, reports The New York Times.
The blow from Hurricane Fiona was made more devastating because Puerto Rico has yet to fully recover from 2017's Hurricane Maria. "If the government didn't learn their lesson with Maria, I hope this disaster wakes them up to our reality," Santiago said.
Human-caused climate change is making hurricanes like Fiona more dangerous, according to a growing body of research. Earth's warmer and moister atmosphere and warmer oceans provide fuel for hurricanes, causing more intense rainfall and wind speeds.
This story has been updated with new information.