Robinson also said he thought his Taser had malfunctioned and only realized the sound he heard was a gunshot when Harrison told officers to take the handcuffs off Scott and give him medical attention.
Robinson testified that Scott did not appear to be threatening enough to justify firing a gun at him.
Also testifying Wednesday were truck driver Dave Wakefield and utility worker Eric Thomason.
Wakefield's tractor-trailer was struck by the car Scott was driving during the chase, and Thomason described the struggle between Harrison and Scott after the pursuit.
“They struggled for the gun, and he (Harrison) managed to hit his (Scott's) hand hard enough on the ground to make the gun slide away,” Thomason said.
“I felt like I was looking down the barrel of the gun they were struggling over,” he said. “I believe the kid was trying to shoot the officer.”
Thomason also testified that he attempted to tackle Scott as he ran by his pickup, and that Harrison fired shots toward him while attempting to wound Scott.
“I was aggravated from the initial fight and shots fired because the shots were fired in my direction,” he said.
Harrison, 48, has pleaded not guilty. He faces four years to life in prison if convicted. His trial is expected to continue through the week.