Acen King, 3, was riding with his grandmother at the time

By Jeff Truesdell
Updated December 20, 2016 12:08 PM

Police in Arkansas are now offering $40,000 as they search for a driver who allegedly engaged in a road rage incident with a grandmother, firing a single gunshot that fatally injured her 3-year-old grandson who was a passenger in the back seat of her car.

The grandmother, Kim King-Macon, 47, was unaware the child had been shot through the car door in the Saturday evening confrontation until she traveled another 10 miles or so to the parking lot of a J.C. Penney store, Little Rock Police Lt. Steve McClanahan tells PEOPLE.

Family members identified the victim as Acen King, reports KATV. His grandmother and a 1-year-old sibling also riding in the car were uninjured.

Acen King
CBS News

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King-Macon had reached a stop sign at the residential intersection of Warren Drive and Mabelvale Cutoff on the city’s southwest side when another vehicle approached hers from behind, police say.

“It was raining,” McClanahan tells PEOPLE. “She was trying to turn. The suspect vehicle honked. She honked back, and then she observed a black male, very generic description, get out with what she thought was a gun.”

“She thought he was going to fire the gun in the air,” he says, before alleging, “He fired in the car. She didn’t know that.”

King-Macon continued driving to the Shackleford Crossing Center, where she planned to meet other family members.

“When they got to Penny’s, she realized the child had been shot,” McClanahan says.

Police, firefighters and paramedics were alerted by a 911 call and the victim was taken to Arkansas Children’s Hospital, where “he died a very short time later,” McClanahan says.

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The police lieutenant was at home eating dinner with his family, including his own 3-year-old son, when he was summoned to the scene on his day off.

Before McClanahan took off, he says, his son told him: “Daddy, give me a hug before you leave.”

“This grandmother and mother will never get to hug this child again,” McClanahan says. “So it does affect us here as police.”

The killing was the city’s 40th homicide of the year. Last year saw 31 killings.

A $20,000 reward has been posted, and police are looking for a vehicle they believe to be a 2003 to 2005 model black Chevrolet Impala. The driver of the suspect vehicle was alone, McClanahan says.

Police have no other description of the driver.

“We are hopeful that with the reward money we have put out, we can generate interest in the case that already had a lot of interest,” McClanahan says. “If someone knows something to sees something, bring it to us to rule out as homicide detectives.”

Asked how King-Macon might have initially missed that her grandchild had been shot, McClanahan says, “It was raining hard. I don’t know if she had a radio on. All I know is that we believe she’s being truthful.”

“We don’t believe that she has any known relationship with the suspect,” he says. “Everything from her side of the story has checked out.”

“We’re looking at this strictly as a road-rage incident.”

Persons with information about the suspect vehicle are asked to call the police tip line at 501-371-4636 or dial 911 locally.

“We don’t want to miss that opportunity to get it,” McClanahan says.