Deadly wildfires in Northern California on Monday forced the evacuation of Medtronic buildings in Santa Rosa that are involved with engineering medical devices to treat diseased hearts and arteries.

Medtronic spokesman Fernando Vivanco confirmed late Monday that Medtronic has four facilities in the Santa Rosa and the Sonoma County region that could be affected by the fires, which have claimed at least 10 lives and destroyed thousands of structures in a wide area north of California's Bay Area.

Medtronic's Fountaingrove and Coffey Lane facilities in the northern section of Santa Rosa were the most at risk of being affected by the fires, Vivanco said. Although the facilities were evacuated per an order from local fire authorities, as of 5 p.m. Monday, it wasn't clear whether the buildings or employees had been directly harmed.

"We are closely monitoring the wildfires in Santa Rosa and Sonoma County, and our first priority is the safety of our employees, many of whom are being evacuated," Vivanco said via e-mail. "We have initiated our business continuity plans and are accounting for and keeping in contact with employees in the area."

Buildings in the region house administrative offices and research-and-development facilities for Medtronic's coronary devices division, which include minimally invasive replacement heart valves and coronary stents, according to securities filings.

It's the second time in less than a month that Medtronic had to activate emergency preparedness plans in response to a natural disaster.

Last month Medtronic's manufacturing operations in Puerto Rico were temporarily closed as a precaution ahead of Hurricane Maria, which made a direct hit on the island Sept. 20. The storm caused dozens of fatalities around the island and knocked out power for residents, hospitals and businesses.

All four of the company's manufacturing sites on the island are at least partly operating with backup power generators, and manufacturing will ramp up in coming weeks. CEO Omar Ishrak said in a news release Friday that the company was "extremely focused" on restoring manufacturing in Puerto Rico "as quickly as possible."

The Puerto Rico closures are expected to cut revenue by as much as $250 million in the quarter that ends Oct. 27. Analysts with Wells Fargo on Monday downgraded the stock, which closed down almost 4 percent Monday, at $76.93.