William Brown had errands to run on a chilly Texas evening, and his grandmother was happy to lend him her light-blue Lincoln Town Car.

Brown stopped at a store selling vaporizer smoking pens outside Fort Worth on Jan. 27. He sat alone in the parked car, put his lips to a pen, and soon after, an explosion sent shards of metal into his face and neck, said Alice Brown, his grandmother.

He thrashed and fell out of the car, trying to regain his balance on the hood and trunk before collapsing, she said, according to evidence from the scene conveyed to her by authorities.

Brown, 24, held on for two days before he died at a hospital. The cause of death was listed as stroke after the carotid artery in his neck was severed by “penetrating trauma from exploding vaporizer pen,” the Tarrant County medical examiner found.

William was the third generation of electricians in the family, said his father, Steve Brown, and they worked side by side.

“He was a real sweet kid,” Brown told The Washington Post on Tuesday, about two weeks shy of his son’s birthday. “Before now I haven’t gone two days without talking to him in 25 years.”

William Brown’s death marks the second recent death from an exploding e-cigarette among thousands of injuries and burns. One man was killed in Florida in May after his vape pen peppered his head with shrapnel and ignited a fire in his home.

There were more than 2,000 vape pen explosion and burn injuries in the United States from 2015 to 2017, according to a study published by Tobacco Control. A report by the U.S. Fire Administration blamed injuries and fires on the prevalence of lithium-ion batteries found in e-cigarettes.

“It is this intimate contact between the body and the battery that is most responsible for the severity of the injuries that have been seen,” the report said.

The health effects of e-cigarette vapor are still being studied by government agencies.

It is unclear what model or type of e-cigarette Brown used, or if he bought it at Smoke & Vape DZ in Keller, the address of which was listed on the medical examiner’s report as the incident location.