Forecasters said Tropical Storm Karen would unleash heavy rains across the northeastern Caribbean on Tuesday that could cause flooding and landslides and strong, gusty winds in Puerto Rico and the Virgin Islands.

As the storm approached, Puerto Ricans were trying to compose themselves after being shaken from their beds late Monday by a 6.0 magnitude earthquake that hit in the Atlantic Ocean off the island's northwest coast at a shallow depth of 6 miles. Three aftershocks, with magnitudes 4.7 and 4.6 and 4.6, followed within less than an hour.

No damage was reported, and communications after the quake were swift because authorities were already on duty for Karen, said Kiara Hernández, spokeswoman for Puerto Rico's emergency management agency.

Tropical Storm Karen's projected path as of 5 a.m. EDT on September 24, 2019 NOAA / National Hurricane Center

Schools and government offices were already ordered closed in Puerto Rico as well as in the U.S. and British Virgin Islands, with officials warning people to stay indoors.

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"We've had a number of these events now, and I know it's like the little boy who cried wolf, but I'm urging the public to remain ever vigilant," U.S. Virgin Islands Governor Albert Bryan Jr. said.

Karen regained tropical storm strength Tuesday morning after having been a tropical depression. Its maximum sustained winds increased to near 40 mph and additional strengthening was expected. The storm was centered about 110 miles south of San Juan and 90 miles southwest of St. Croix. It was moving north at 7 mph.

Karen was expected to keep heading north after passing over Puerto Rico and stay well east of the Bahamas, the U.S. National Hurricane Center said. A tropical storm warning remained in effect for Puerto Rico, Vieques, Culebra and the U.S. and British Virgin Islands, and forecasters said certain areas could experience stronger winds.

Puerto Rico Governor Wanda Vázquez activated the National Guard on Monday and urged people in flood-prone areas to seek shelter.

The island is still recovering from Hurricane Maria, which hit as a Category 4 storm two years ago and is estimated to have caused more than $100 billion in damage. More than 25,000 homes still have blue tarps for roofs and the electric grid remains unstable.

"It's a reality that we might have power outages," Vázquez said.

Roberto Garcia, meteorologist in charge of the National Weather Service's San Juan office, said 2 to 4 inches of rain was expected with up to 8 inches in isolated areas by the time the storm passed by on Tuesday. He added that some towns in the eastern part of Puerto Rico would likely be hit with moderate to serious flooding, especially those next to mountains.