(CBS) — A new clue in the investigation into a deadly hit and run in Michigan City, Ind.

Police believe the driver of a car captured on a surveillance camera may have fatally struck 5-year-old Delaney Klewer and never stopped.

“He didn’t care that there was little girls on the road. He didn’t stop.”

Eight-year-old Sara Klewer describes the moment a hit and run driver killed her sister, Delaney, as they were crossing the street.

“I would still be playing with her and everything.”

The sisters were playing at Water Tower Park when they crossed Broadway to head home just before 6 p.m. Tuesday. That’s when the younger girl was struck. Sara ran to the house, to tell her mother what happened.

“It’s a nightmare. That’s the only way I can describe it,” the mother, Gail Lynn Smith, says.

Police released a surveillance image of what they’re calling a vehicle of interest. It appears to be a dark gray or black SUV. It was captured by a nearby factory camera, moments after the hit-and-run.

The driver was going down Broadway, where a 15 mph zone is posted because of the park. Police say the motorist could be a resident of the area or someone who works at one of the nearby factories.

On Wednesday, stuffed animals and a wooden cross mark the spot, where the child landed, after the impact. Her father held Delaney as cars rushed by.

“People came down here, at least four cars, doing at least 40 to 50 miles an hour,” Matthew Klewer says. “You shouldn’t be doing that by a park. Come on people, some common sense.”

Local authorities plan extra police patrols in the area to make sure motorists do not speed. Meantime, a $5,000 reward is being offered to help find the motorist who struck the child.