By Nick Janes

SACRAMENTO (CBS13) — Working the late shift at A&P Liquors, Eric Cain stood on a Sacramento street corner early Thursday morning watching an argument-turned-fight he had no idea was about the make international heroes.

Cain says the whole thing appeared to start over a girl, and Spencer Stone was stabbed trying to defend her.

“Right now we’re sitting there going, ‘I don’t think they’re gonna fight; they don’t want to fight,’” Cain said, re-watching the surveillance video.

BREAKDOWN: A Closer Look At The Fight That Led To Spencer Stone Stabbing In Sacramento

Cain says the whole group came from the direction of Badlands, a club down the street.

“Obviously they had left the club together,” he said. “They knew each other or something; they had been hanging out before this happened.”

EXCLUSIVE: Cab Driver: Suspect Punched Woman In Fight That Led To Spencer Stone Stabbing

It looked to Cain like a young woman was fighting with her boyfriend.

“She’s hitting him with a plastic bag,” he said.

He thought the fireworks were just about over as the group started separating.

“Kinda arguing, kinda hem-haw fighting, pushing and stuff. We didn’t think they were gonna fight and that’s when I started walking back to the store, and that’s when I heard a (punching sound) and I turned back around,” he said.

Cain says the man hit by the woman with a bag punched her in the face. Stone got in the middle of it.

“And the big dude the white guy stood up and kinda got in his face,” he said.

In the ensuing brawl, Stone was outnumbered and stabbed several times, but the airman didn’t cry out in pain or stumble.

“He didn’t look hurt at the time. He was walking with his arms up, you know how you are after you get in a fight,” he said. “I saw the back of his shirt—there was a big red mark on the back of his shirt and another guy walked by and I just kinda went, ‘I think the dude got stabbed.’”

Cain said he was even more surprised to see the woman got in a car and left, not with Stone, but with the suspects.

“I thought she was with the white guy the whole time because he was sticking up for her but she ended up leaving with the Asian guys,” he said.

He’s worked there for 20 years, but says he’s never seen anything like this happen before.