DETROIT -

Detroit police detectives are investigating after a grandfather was gunned down Thursday while he was mowing his lawn.

If that's not devastating enough, the victim's 6-year-old grandson watched it all go down. So did a neighbor who has asked not to be named in this story.

"It sounded like a fire cracker to me. It was just bang, bang bang. I know I heard at least five or six shots," the neighbor said. "We went down to see what had happened and we saw this fella, our neighbor, laying on the sidewalk, and blood was coming from his face or neck, and he was face down on the sidewalk."

Police sources tell Local 4 about 4 p.m. a white SUV rolled down Glendale Avenue. The passenger jumped out firing five shots, killing the man who is a father or four and a grandfather of four.

"It's just a shock. The gentlemen was a very nice gentlemen. He was always taking care of his home. He's got a very nice family. It's just a very sudden thing," said neighbor Bill Walton.

The attack was not random, police say. The victim owed the suspects some cash and when they came to collect the money they instead used a gun to settle the score.