A multiple-alarm fire broke out in a home in Harrisburg, Penn., on Friday, killing a 3-year-old girl. Officials traced the blaze to a hoverboard that caught fire while plugged in to an electrical socket on the three-story house’s first floor.

“They heard some sizzling and crackling in the hoverboard and shortly thereafter, it exploded in flames,” Brian Enterline, the city of Harrisburg’s fire chief, told the Associated Press.

A spokesman for the U.S. Consumer Products Safety Commission, Scott Wolfson, told NBC News that the fire was the first fatal incident linked to hoverboards. The agency has probed 60 cases of hoverboard fires in the past year and a half, NBC News reported. The investigation into the fire is ongoing.

After the scooters emerged as one of the hottest gifts of the 2015 holiday, reports of hoverboard fires soon began to surface. The devices’ rechargable lithium-ion cells contain a potentially flammable solution, which can explode if the battery is damaged or defective.

Ying Jiawei, chief executive of Chic, one of the first companies to sell hoverboards in Asia, lamented to Fortune last year that Chinese factories were cutting corners with the devices, subbing in cheaper batteries. “We have licensed to 30 factories, but only a few follow our rules,” Ying told Fortune.

By February 2016, hoverboards had caused two homes to burn down, as The Washington Post reported. By the middle of 2016, the Consumer Products Safety Commission warned that consumers should stop using hoverboards made by certain manufacturers. Hoverboard sellers recalled more than 500,000 of the self-balancing boards in July. Major airlines banned the boards, citing the fire danger.

The Harrisburg blaze was the first hoverboard fire to be reported as lethal. Three-year-old Ashanti Hughes died in a hospital Saturday, the Lehigh County coroner’s office said. Two other girls remained in critical condition, according to the AP. Hughes’s father and a male teenager were treated for inhaling smoke and have been released from the hospital.

“My granddaughter, I can’t replace her,” Mark Hughes, Ashanti’s grandfather, said to Fox43. “The pain is so deep. I’m so hurt. My soul is hurt.”

A firefighter also died while responding to the blaze. Lt. Dennis Devoe, a 21-year veteran of the Harrisburg department, was killed en route to the fire station when another car struck his vehicle. Officials said that Khanyae Kendall, a 19-year-old woman who they say was driving a stolen car while intoxicated, was responsible for the crash. She has been charged with aggravated assault by motor vehicle, according to Penn Live, as well as driving under the influence and other traffic offenses. It was unclear whether Kendall, who was not able to post a $200,000 bail, had an attorney.

Fox43 reported that Pennsylvania Gov. Tom Wolf ordered flags at the state’s capitol to fly at half-staff in DeVoe’s honor.

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