TORONTO -- A 12-year-old boy is being hailed a hero for saving his great-grandparents in a stabbing attack that could have resulted in two murders, according to a Texas sheriff.

Harris County Sheriff’s Office was alerted on Sunday night about two stabbing victims, aged 92 and 76, Sheriff Ed Gonzalez wrote on Facebook. 

The initial report was that the seniors were driving with their great-grandsons Lucian Johnston, 20, and Sacha, 12, when an argument broke out and Johnston began stabbing his great-grandparents from the backseat.

“The real hero in this ordeal is a 12-year-old that was also in the backseat at the time of the brutal attack,” Gonzalez wrote.

“He managed to wrestle the knife away from Johnston and threw it out the window, which successfully stopped the attack.”

According to local media, the great-grandparents were taking Johnston to a friend’s house, after they said he could no longer live with them due to concerns over recent violent behaviour.

Johnston then began stabbing his 92-year-old great-grandmother and 76-year-old great-grandfather in the head and neck with a pocket knife, according to deputies.

The younger boy, named locally as Sacha, said he wrestled the knife away from Johnston.

“I grabbed him from behind the shirt. I pulled him backwards, trying to get him away from grandma,”Sacha said.

“I did grab the knife. I held that to his neck also. He bent back my finger, which is still sore. He head-butted me, which I have a loose tooth from that, but I do not really care.”

Johnston gave up the fight and ran from the scene.

“I’m still looking at the knife in my hand, so I take it and throw it outside, shut and lock the door,” Sacha said.

“I yell at her (his great-grandmother) to shut and lock her door. At least I was there to stop it.”

Deputies told KSLA News that the seniors drove themselves to the hospital. Gonzalez said both victims are recovering well.

“Our team worked around the clock. This morning, the grandson, Lucian Johnston, was arrested and charged with aggravated assault,” Gonzalez wrote Monday.

“He was arrested without incident. Great work by all, this very easily could’ve resulted in two murders.”

None of the allegations have been proven in court.