CHANDLER, AZ (3TV/CBS 5) – Police say a car explosion at a Chandler gas station was caused by a man who might have been impaired.
"I heard a bang and came outside and saw all the smoke and started hearing the tires pop from the car," one witness said.
It happened just before 1 p.m. on Thursday at the AM-PM Arco at Chandler Boulevard and Alma School Road.
[WATCH: Witnesses explain what they saw]
Video from the Arizona's Family News Chopper showed tow trucks hauling the burned cars away.
According to police, Clemente Torres parked at a pump and went into the store to pay for some gas.
[WATCH: First report]
Police say the 21-year-old realized he was at the wrong pump, got into his car and sped around the pumps, hitting a 77-year-old woman who was filling up her car.
Cellphone video shot by Robert Waite shows the front end of Torres' car on fire right before the explosion. The burning car was nudged up right behind the woman's car.
"Tires were squealing. There was rubber burning," Waite said. "From my perspective, it looked like she was on fire because she had this little -- as soon as he took out that pump -- there was a little ball of flame."
The woman Torres allegedly hit was taken to the Maricopa County Hospital Burn Center. Police say she suffers from second-degree burns to her hands, head, neck and body.
Waite also says there was a good Samaritan involved.
"He just ran right in and grabbed her, along with another guy, and got her out of harm's way -- immediate harm's way," he said.
Torres and an AM-PM employee tried to put out the fire with both water and a fire extinguisher, but they could not do it.
Waite also captured a photo that police confirm shows Torres running away.
[PHOTOS: From the scene]
When police got in touch with Torres' family, according to court documents, they said he was on his way to DUI Veterans Court in Tempe for a previous DUI arrest when this incident occurred.
Once police eventually found Torres, court documents say they smelled a strong alcoholic odor on his breath.
Following this, Torres was placed under arrest, and he is now under investigation for impaired driving.
Torres faces charges including aggravated assault, leaving the scene of an accident and endangerment.
When taken to the headquarters of the Chandler Police Department, Torres scored a .241 BAC during his field sobriety tests. Torres also went through a warranted blood test.
Police say there is surveillance video of the explosion and fire, but they will not be releasing it right away.
The cost of damage made to the vehicles, gas pump and overhang is estimated to $25,000, court documents confirm.