Medical device maker Medtronic took its five production plants in Puerto Rico temporarily offline on Tuesday following a wave of earthquakes that has left residents rattled and much of the island without a working power grid.

The Medtronic factories were expected to resume normal operations by Tuesday night or Wednesday morning, Medtronic spokesman Ben Petok said. While the plants themselves did not sustain significant damage, operations were halted as employees assessed their own situations and tended to personal needs. The closures are not expected to have a material financial impact for the global med-tech manufacturer.

Puerto Rico, which was struck by massive Hurricane Maria in September 2017, was hit on Tuesday by an earthquake that registered 6.4 on the Richter scale after more than a week of smaller quakes. One fatality was blamed on Tuesday morning's temblor, and CNN reported that close to 300,000 of the island's 1.1 million utility customers were without power as of Tuesday afternoon as aftershocks continued. Puerto Rico Gov. Wanda Vazquez told reporters Tuesday that the island was under a state of emergency, with quakes expected to continue for several more days. Federal officials with FEMA said Tuesday afternoon they were still evaluating the governor's request for an emergency declaration.

Medtronic, run from offices in Fridley, has manufactured pacemakers and other medical devices on the island since the 1970s. Today the island is home to a biosciences industry that comprises a third of the island's entire economic output, and Medtronic makes up more than 45% of those industrial jobs, Caribbean Business reported last October.

"The safety of all of Medtronic's more than 4,000 employees in Puerto Rico is our primary concern," Petok said via e-mail Tuesday afternoon. "At this time, we are working to gather information regarding any specific injuries to employees or damage sustained to property. We are working with local authorities to understand the conditions across Puerto Rico, particularly on the southern part of the island, and will provide information as it becomes available."

Medtronic has facilities in the cities of Ponce and Villalba, near the epicenter of Tuesday's earthquake off the island's southwest coast. Medtronic also has plants in the cities of Humacao and Juncos to the east and San Juan to the north. The company produces a wide variety of heart devices, diabetes-management systems and minimally invasive surgical products on the island.

Medical device maker Boston Scientific Corp., which has a major business presence in Minnesota, said Tuesday afternoon that its facility in Dorado, on the northern coast, was fully operational and its employees were safe following the quakes.

"We will continue to assess our employees' needs and provide additional support as needed," spokesman Kate Haranis said via e-mail.

Maplewood-based 3M Co., which has two small offices on the northern side of Puerto Rico, said all of its employees there are safe and business operations are continuing with the help of power generators.

The U.S. Geological Survey reported Tuesday that hundreds of smaller earthquakes have been registered just off shore in the same region since Dec. 28.

The seismic activity stems from the fact that the North America tectonic plate and the Caribbean plate are converging at a rate of 20 mm/year near the epicenter of the quakes, which has likely led to undersea "intraplate" tectonic motion on the Caribbean plate that Puerto Rico rests upon.