'Keep calm': 6.0 earthquake rattles jittery Puerto Rico as Tropical Storm Karen strengthens

A magnitude 6.0 earthquake rattled Puerto Rico hours before Tropical Storm Karen began pounding the island still recovering from the devastation of Hurricane Maria two years ago.

No serious damage or injuries were immediately reported from the quake, centered about 50 miles northwest of the island when it struck just before midnight Monday. Several strong aftershocks further rocked many residents.

Gov. Wanda Vázquez Garced closed schools and government offices Tuesday and urged residents to remain calm.

"We hope everyone is well," she tweeted, adding that there was no risk of tsunami from the quake. "We have no harm in the face of the strong tremor."

Rain began sweeping the island Tuesday as Tropical Storm Karen closed in. At 5 p.m. the storm was centered 35 miles southeast of San Juan and moving north at 8 mph. The National Hurricane Center issued a tropical storm warning, forecasting strong winds.

Karen's maximum sustained winds increased Tuesday to 45 mph with higher gusts, and the storm was forecast to strengthen over the next two days. 

"The center of Karen will pass near or over Puerto Rico and the Virgin Islands this afternoon and then move over the western Atlantic tonight and Wednesday," the hurricane center said Tuesday.

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Puerto Rico's Bureau of Emergency Management and Disaster Management opened shelters in anticipation of flooded homes.

“We must remember that we are in the most active period of the hurricane season – and we should not lower our guard," Department of Public Security chief Carlos Acevedo Caballero said.

He said everyone should have a family emergency plan and urged people to stash water and food supplies for a minimum of 10 days per family member, including pets. Residents should become familiar with the location of the nearest shelters, have passport, medical plan cards and other identification information and prepare an emergency backpack, he said.

Some isolated areas of Puerto Rico could see 8 inches of rain, enough to touch off flooding and mudslides in areas still healing from the fury of Hurricane Maria, a Category 5 giant blamed for 3,000 deaths and $90 billion in damage two years ago. Thousands of Puerto Ricans live in housing that has not been fully repaired.

"Prepare and keep calm," Housing Secretary Fernando Gil Enseñat said.

Elsewhere, Tropical Storm Jerry weakened a little Tuesday as it edged closer to Bermuda. Jerry had top sustained winds of 50 mph and was moving to the north at 6 mph. It was about 260 miles west-southwest of Bermuda on Tuesday afternoon.

Contributing: The Associated Press