The suspect in an attempted Utah carjacking messed with the wrong grandma.

Authorities say 69-year-old Frances Mach pulled into the driveway of her daughter’s Saratoga Springs home on Saturday, where 38-year-old Christopher Bigler jumped into her car and told her to drive.

Bigler then allegedly slapped the 69-year-old grandmother, but she fought back.

“I just balled up my fist and I nailed his head about three or four times and told him to get out of my car,” Mach said.

Police say Bigler fled the car and headed for Mach’s daughter’s home. They say he then locked himself in the apartment and set it on fire.

Authorities doused the flames and apprehended the suspect, who police believe was under the influence of methamphetamine.

Bigler is in critical condition in the hospital, where he is being treated for burns and smoke inhalation.

Mach was not harmed, though she said she had a minor shoulder ache from hitting the suspect.

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