A 24-year-old man from Fort Worth, Texas, died last week after a vape pen he'd recently purchased exploded in his face and severed his left carotid artery, according to the Tarrant County Medical Examiner's Office.

The fatal incident unfolded moments after William Brown, who'd borrowed his grandmother's car to run some errands, stepped out of a Smoke & Vape DZ store at a nearby shopping mall on January 27 with his very first electronic cigarette.

Disaster struck after after Brown returned to the vehicle and "popped" the device open, according to Alice Brown, his grandmother. The battery exploded, melting plastic in her car and send debris into William's face and neck.

Screenshot/WFAA Texas man William Brown dies after vape pen explodes, severing his left carotid artery.

"He popped it, and it exploded, and that's when it shot across his mouth," she told local news station WFAA. "When they x-rayed him, they found the stem, the metal embedded to where the blood flows up to the brain."

"I miss him already, and knowing he won't open that door and come through it ever again is the hardest part," she added.

Local media reports indicate that after the explosion, William was able to get out of the vehicle to search for help; however, he ultimately collapsed near the trunk of the car. An ambulance was called after William was spotted in the parking lot, and he was transported to the John Peter Smith Hospital, where he died two days later.

The medical examiner's report ruled William's cause of death as "penetrating trauma from exploding vaporizer pen" which led to a the "dissection of left internal carotid artery" and "cerebral infarction and herniation." The report notes William's time of death as 3:45 p.m. local time on January 29.

Alice told local newspaper the Fort Worth Star-Telegram that William had never been a smoker, and that he'd shown interest in vape pens after he was informed that a certain type of electronic cigarette could help him with his asthma.

It's presently unclear what brand of vape pen William purchased at the Keller store. Furthermore, Alice told the Star-Telegram that she did manage to find the pen's battery, which still had the serial number, when searching her car.

"That's the important part," Alice said. "That's what the investigator said he needed…. I just hope, if anything, I hope it stops someone from [smoking electronic cigarettes]. I don't know how many more people will have to die."

William was just a few weeks shy of his 25th birthday. "It just hurts so bad… Now he'll never see that birthday. It's a waste of the things he could have accomplished," Alice added.

William is the second reported person to have been killed in the US by an exploding vape pen. Last year, in May, 38-year-old Florida resident Tallmadge D'Elia was killed after his e-cigarette exploded and lodged projectiles into his skull. D'Elia also suffered burns to roughly 80 percent of his body.

A July 2017 published report from the US Fire Administration, a division of the Federal Emergency Management Agency, found that between January 2009 and December 2016, there were 195 explosions and fires involving vape pens that were reported by the US media. Of those, 133 resulted in acute injuries, and 30 were deemed severe.