A second child has died in a fire that began when a hoverboard malfunctioned in Harrisburg, Pennsylvania. Savannah Dominick, 10, succumbed to burns covering 95 percent of her body Thursday, NBC Philadelphia reports. Ashanti Hughes, 3, was pronounced dead Saturday morning, the day of the fire.

The tragic deaths have emboldened federal officials, who launched an investigation into whether or not the faulty hoverboard was among the brands that were recalled last year. Despite their popularity, these so-called hoverboards have been the subject of intense public scrutiny, after a rash of explosions occurred as a result of faulty batteries and internal mechanisms.

Senators Robert P. Casey, Jr. (Pennsylvania) and Amy Klobuchar (Minnesota), wrote an open letter to the U.S. Consumer Product Safety Commission’s acting chairwoman, Ann Marie Buerkle, asking her to “identify whether the hoverboard involved was included in the July 2016 recall.” If not, the open letter said, the recall needs to be expanded.

Buerkle released a statement in which she extended her thoughts and prayers to the two children, and explained the nature of her investigation. “An important part of our investigation is determining the make and model of the hoverboard,” she said. “We want to know whether the hoverboard was a previously recalled model or a different model that would need further analysis by CPSC technical staff. I urge consumers who own a hoverboard to check to see if it has been recalled."'