Ottawa police said Monday that a 4-year-old boy was killed Saturday afternoon when he was struck by a vehicle without a driver that had rolled down the driveway.

Lt. Adam Weingartner said the incident happened moments after someone had returned the vehicle home to the 1000 block of South Cottonwood Street, but he did not identify the last driver of the vehicle.

He said police have interviewed the boy’s mother, a 41-year-old Ottawa woman, and a boyfriend, also 41 from Ottawa, who were present when the incident happened.

Officers were called just before 3 p.m. Saturday to the residence for a possible injury accident. The boy later died from his injuries at Ransom Memorial Hospital in Ottawa. Police did not release the name of the boy Monday.

“Police collected evidence that will be sent to the Kansas Bureau of Investigation laboratory for analysis,” Weingartner said in a statement. “Alcohol may have been a factor.”

Members of the Franklin County Sheriff’s Office’s accident investigation team assisted police. He said officers would continue the investigation and forward information to the Franklin County Attorney’s Office for a decision on filing any possible criminal charges.

No one has been arrested.