Joe Cassidy had no idea what he was walking into when he emerged from his service station to investigate the loud car crash on Highway 1A, roughly 65 km northwest of Calgary.

A stolen Audi Q7 SUV had been T-boned and thrown from the road by the impact after it attempted to gas-and-dash from the Ghost Station gas bar on Tuesday.

Ghost Station cameras captured the attempted gas and dash and ensuing collision on Highway 1A. 0:17

Cassidy, the campground manager there, made his way to the collision and said he asked the two female occupants of the SUV to sit and wait for police to arrive.

That's when both women took the opportunity to flee on foot.

"They ran down a hill and into a ravine, and I gave chase on an ATV to try to catch up, 'cause I was in my bare feet," Cassidy told CBC Calgary News at 6.

As he gave chase, Cassidy said he was "basically yelling commands.

"The police dogs are coming. You might as well give up. There's no sense in running. We're gonna find you," he told them.

Cassidy said he managed to catch up to one of the women. "I told her, 'You stay right there. I'm making a citizen's arrest. You don't go anywhere. I'll use force if I have to.'"

CBC News Calgary at 6 speaks with Joe Cassidy about an attempted gas and dash earlier in the week. 3:24

Police lay charges

Tarensa Marie Kootenay, 27, and Karine Leora Beaver, 26, were both later arrested by police and are now facing a number of charges.

"I'm thankful for that, 'cause they need a tough lesson," Cassidy said.

"To think that you can run away from something like that and not be responsible is absolutely ridiculous to me."

Kootenay is charged with:

Posession of stolen property over $5,000.

Theft under $5,000.

Failure to remain at the scene of a collision.

Failure to comply with an undertaking.

Failure to obey a stop sign.

Beaver has been charged with two counts of failing to comply with an undertaking.

In a release, Const. Kary Moore of the Cochrane RCMP thanked the witnesses for their assistance prior to police arrival.

Cassidy said this isn't the first citizen's arrest he's performed.

"I think it's my duty and everyone's duty to protect each other. Police are strapped. They can only do so much," he said.

"If they're not there for 15, 20 minutes, we can't just stand idle and watch what's happening. You have to do something about it. You have to jump in and help any way you can."