By Charlie De Mar

CHICAGO (CBS) — Michelle Zavala had only seconds to react when two men attacked her from behind, and her decision turned out to be the right one.

“I can’t believe I screamed that loud,” she said. “I didn’t know I had it in me to scream that loud.”

That scream likely saved her life, and she’s sharing her story in hopes of educating others who might find themselves in similar frightening scenarios.

“He came up behind me and put me in a choke hold,” she said. “I was about to black out because I started seeing really blurry.”

Surveillance video from early Saturday morning shows Zavala walking down Central Park Avenue between Ogden and Cermak when two men grab her from behind.

“I always have my pepper spray with me,” she said.

She said she’s not sure if the men wanted valuables or her.

“If he wanted to rob me, he could have taken my phone, my money, something,” she said.

Her scream got the attention of Frank Diaz, who can bee seen in the video running to Zavala, sending her attackers running.

“I reacted quickly,” he said. “Quickly enough. Within 10 seconds I got to them.”

Diaz said he noticed the men right before they attacked and was suspicious.

“It was 90 degrees out wearing a hoodie, covering your face? They were up to no good,” he said.

“I’m so, so thankful,” Zavala said. “If it wasn’t for him I probably wouldn’t be here right now. I don’t know what they wanted to do to me.”

Those two men ran off and are still on the loose.

Charlie De Mar