U.S. safety regulators are investigating a fire in Texas that destroyed three vehicles this month, including a luxury plug-in sports car built by Fisker Automotive.

The Fisker Karma, which sells for more than $100,000, was parked in the garage of a newly built home in Sugar Land, Texas, when the fire broke out.

The National Highway Traffic Safety Administration has sent investigators to inspect the site, but has not opened a formal investigation. “NHTSA is working with local authorities to evaluate whether there are any potential safety implications and will continue to monitor the situation,” the safety agency said in a statement.

Fisker could not immediately be reached for a comment.

After the fire, the Karma’s lithium-ion battery was intact, suggesting it was not a “contributing factor,” Fisker said at the time, adding that the Karma was not plugged in.

The safety of electric car batteries has been in the spotlight since last year when U.S. safety regulators opened an investigation into General Motors Co.’s Chevrolet Volt after some battery packs caught fire during testing.

NHTSA closed the probe in January, saying that electric cars do not pose a greater risk of fire than gasoline-powered cars.

Fisker has faced tough questions about the reliability of the Karma after a spate of high-profile battery problems in recent months.

In March, a Karma battery failed during a test conducted by Consumer Reports magazine. Fisker recalled 239 Karma cars in December to fix a battery defect that raised the risk of a fire.

The Karma that was destroyed in the garage fire was purchased after the recall. No fires or injuries have been tied to the Karma battery, which is built by A123 Systems.

(Reporting By Deepa Seetharaman in Detroit)