A Calgary man who was seriously injured in a road rage-related stabbing says his attacker didn't say a word to him, but simply stabbed him in the chest and looked him in the eyes before fleeing.

David Nickerson was rushed to hospital in life-threatening condition Tuesday morning, after the attack in the parking lot of an Auto Value store in Calgary. Nickerson says he thought he was going to die, but the knife attack narrowly missed his heart and cut his diaphragm instead.

"I'm doing much better now," Nickerson told CTV Calgary by phone on Wednesday. "The blood is not quite as severe around my heart… They've got the perforation in my diaphragm sewn up."

Nickerson says the man was clearly angry about something that happened on the road, but he doesn't think he did anything wrong to provoke the attack.

Security footage from the scene shows Nickerson pulling into a parking spot in front of the Auto Value, seconds before a red truck pulls up and stops behind Nickerson's car, blocking him in. Nickerson can be seen getting out of his car and circling around to stand between the two vehicles, where he waits as the driver of the truck gets out. The suspect can be seen approaching Nickerson, and as the two come together, Nickerson suddenly jolts backward, clutching his chest.

"I thought he was poking me with his fingers," Nickerson said. "Then I felt a hot feeling and touched my chest and I realized it was blood, and I ran."

The suspect can be seen taking a few more steps toward Nickerson before turning around to get back into his truck and leave.

Nickerson says his attacker did not say a word, but did stare him down after the stabbing. "He looked me in the eyes right after he stabbed me to see what was going to happen to me," Nickerson said.

Nickerson stumbled into the Auto Value after the attack, where staff tended to him until an ambulance arrived.

"It was horrifying," Auto Value manager Janice Scrivens told CTV Calgary. She said Nickerson is one of the store's "best customers," and she plans to launch a fundraiser to help him with medical expenses. "We're going to do everything we can to support him," she said.

Calgary police arrested a suspect in connection with the stabbing on Tuesday, following a six-hour standoff at a residence in the city's southeast. The man is also accused of a separate road rage incident that occurred 20 minutes prior to the stabbing.

In the earlier incident, police say the suspect yelled at a pedestrian and struck him with his truck, then tried to strike him again. "However, the pedestrian was able to dive out of the way," police said.

Charges were pending as of Wednesday night.

With files from CTV Calgary