Jessi Combs, professional racer and former Mythbusters host, has died while trying to break a land-speed record in Oregon’s Alvord Desert, her family said in a statement to news outlets. She was 39. The Harney County Sheriff’s Office Wednesday confirmed Combs’ death and said the cause of the accident was under investigation.

Combs was co-host of the Spike TV show Xtreme 4×4 for more than 90 episodes from 2005 to 2009. She also appeared on shows including Overhaulin’, Mythbusters, The List: 1001 Car Things To Do Before You Die, All Girls Garage and Science Channel’s How to Build… Everything in 201.

Combs was attempting to beat the 512-mile-per-hour women’s land-speed record set in 1976 by American Kitty O’Neil, who died last November.

Combs appeared in several episodes of Discovery’s Mythbusters, filling in for host Kari Byron while Byron was on maternity leave. Mythbusters host Adam Savage and Byron both posted remembrances on Twitter.

“I’m so so sad, Jessi Combs has been killed in a crash,” Savage wrote. “She was a brilliant & too-notch builder, engineer, driver, fabricator, and science communicator, & strove everyday to encourage others by her prodigious example. She was also a colleague, and we are lesser for her absence.”

Byron also tweeted, “So sad to hear about Jessi. She was a badass. Always pushing limits. Sending smiles into the universe for her.”

In a posting on social media this week, Combs wrote, “It may seem a little crazy to walk directly into the line of fire… those who are willing, are those who achieve great things. People say I’m crazy. I say thank you.”

I’m so so sad, Jessi Combs has been killed in a crash. She was a brilliant & too-notch builder, engineer, driver, fabricator, and science communicator, & strove everyday to encourage others by her prodigious example. She was also a colleague, and we are lesser for her absence. — Adam Savage (@donttrythis) August 28, 2019