A road rage incident sends one man to the hospital and the other on the run.
He thought about just driving by, but Michael Slaughter says it wasn't the right thing to do.
"The guy was just driving so crazy," Slaughter said.
He saw a road rage incident, involving two other vehicles unfold at the HEB on Riverside Drive.
Slaughter added, "I kind of followed them to make sure the guy wasn't going to attack."
It continues at an intersection just before the Canyon Oaks Apartments.
"The guy gets out of his truck again and tells them to pull over," said Slaughter.
Police say the victim lives in this general area, but he didn't want to drive home, so instead, he pulled into this parking lot.
Slaughter added, "The guys begins to sprint towards a Hispanic male that jumped out of the truck...the next thing you know, the guy's just stabbing him."
"We know it was a knife...it's been described as approximately five inches," said Cpl. Ken McDonnell, with the Austin Police Department.
"He had blood all over his shoulder, his back and all over his hands," said James Smith, who lives just a few feet away from the scene, in the 1700 block of Burton Drive.
Smith said, "It's a little disturbing...I wouldn't want to experience that."
"I turned around immediately, I said, this has got to stop. As I turned around, the guy sprints back into his truck," Slaughter said.
Michael followed the suspect, taking down what information he could.
Cpl. McDonnell said, "He last got into his vehicle, which is a late 90's or early 2000 maroon or dark, small SUV, headed southbound on Burton Drive."
The victim wasn't the only one inside the truck.
"It was a girl and her mother and step-dad. I actually just left from where they are...prayed with them, counseled with them...they seem to be doing really well," said Slaughter.
Police say to call 911 if a driver with road rage ever starts following you.
The suspect is still on the loose.
Police are looking for a light-skinned African-American man in his 40's. He is 5' 8" with a thin build and a light colored goatee. He was last seen wearing a cowboy hat, blue button up shirt and in a maroon or dark SUV.
If you see anyone matching this description please call police.