A woman’s death is under investigation after a defibrillator fire and explosion burned her during treatment at a Texas hospital, reports Newsweek.

The fire occurred while staff at HCA Houston Healthcare Kingwood were attempting to resuscitate COVID-19 patient Denise Jill Asaro, 69, of Cleveland, Texas. Houston police said the fire also caused a small explosion, according to ABC 13 news. The cause of the fire is under investigation.

Asaro’s niece, Kristi Robbins, said the incident caused significant burns to her aunt. Robbins told ABC 13: “It was literally her entire upper torso that was burned horribly, to the point of having to have a closed casket.”

Police have launched an investigation into the woman’s death. It is not yet known whether Asaro died due to the fire or another factor.

Read more in Newsweek.