An armed Arizona man last week detained a murder suspect, who allegedly ran over another man with his car multiple times and stomped his head, until police arrived.

Emmanuel Reynoso Avila described to FOX 10 Phoenix how he and his brother jumped into action in Mesa on Friday after witnessing a car strike his neighbor, 63-year-old Christopher Heimer, and send him flying through the air.

"I dropped everything I had, and I ran inside to get my gun while [my brother] was calling first responders," Reynoso Avila said. "Then I shot off at the ground toward the driver because [the suspect] was trying to leave the area after he had run him over a second time."

Heimer was pronounced dead at the scene, the Mesa Police Department said.

FLORIDA K-9 TAKES DOWN SUSPECTED CAR THIEF DURING CHASE: ‘GET HIM OFF, PLEASE!’

John Lagana murder suspect

John Lagana, 61, was charged with first-degree murder, police said. (Mesa Police Department)

Officers had responded just after 12:30 p.m. to multiple reports of someone intentionally using their vehicle to run over another person, police said. 

Police said a witness used their own firearm to shoot a round into the ground and prevent the suspect, identified as 61-year-old John Lagana, from leaving the scene until officers arrived to take him into custody.

After speaking with witnesses and reviewing surveillance footage, investigators said they determined that Heimer was walking on a sidewalk when Lagana swerved off the roadway and struck him.

Lagana continued driving on the sidewalk, according to authorities, taking out mailboxes and landscaping before turning around and speeding toward Heimer again.

"Witnesses say Lagana again drove onto the sidewalk, into the landscaping and ran over Heimer, who was already lying injured on the ground," police said. "Lagana then got out of his vehicle and proceeded to stomp on Heimer’s head multiple times."

PENNSYLVANIA MAN ACCUSED OF PLOWING INTO CROWD, MURDERING MOTHER SAID HE WAS TIRED OF ARGUING WITH HER: REPORT

Arizona crime graphic

Then Reynoso Avila stepped in.

"At that point, I aimed back up at him," Reynoso Avila told the station. "Let him know that I was going to make sure that he didn’t get away, that I was going to shoot if he attempted to flee the area, which he was. I got him out of the car with his hands up and held him there until the police arrived."

Police said Lagana was waiting for Heimer in a vehicle outside the victim’s residence. Skid marks were discovered throughout the scene where Lagana was believed to have accelerated when driving toward the victim.

Lagana told police that his ex-girlfriend was living with Heimer, the station reported, citing a police report. No further details were immediately available.

CLICK HERE TO GET THE FOX NEWS APP

Lagana was booked into jail on first-degree murder charges and held on a $2,000,000 bond.