Doctors say a witness may have saved a woman’s life after she was hit by an out of control car on her morning walk in Gwinnett County Friday.

Surveillance video shows the devastating crash on Satellite Boulevard. Police say a young driver lost control of his car and slammed right into the woman, severely injuring her.

“She never saw it coming,” said Benjamin Jahnke, who witnessed the crash. “The car pretty much faceplanted her in the dirt.”

Jahnke was across the street at EMC Security when he heard the crash around 9 a.m. He says he and his coworkers immediately rushed across the street.

“My parents always told me whatever happens, stay calm,” Jahnke said.

Jahnke says his Boy Scout training kicked in, and he quickly used his belt as a tourniquet to stop the bleeding. Doctors called him a hero, saying that move may have saved her life.

Jahnke said it took the woman a minute to realize that the crash cut off her foot.

“If she went to try to stand up, she would realize that she couldn’t,” he said.

James Collins helped keep the woman's eyes off of her legs as they waited for paramedics to arrive.

“I was making sure that she knew I was there, making sure she knew I was taking care of her,” Collins said.

After both men saw the video of the horrific crash, they say it's clear that two cars were speeding before the Mustang lost control.

“Someone carelessly driving a high performance vehicle has shattered the lives of a family for nothing,” Collins said.

He says coming to work on Satellite Boulevard will never be the same again.

“Regardless of whether I’m driving through that spot or lying in my bed at night, that thought will race through my mind forever,” he said.

But both men say they hope that's not true for the woman they helped.

“I pray that one day we can see her again jogging up and down,” Jahnke said.

The woman had to have her leg amputated and is recovering. Police say the teenager could face charges in the crash.