HARRISBURG, Pa. — Police investigating the shooting death of a Maine man along an interstate highway in Pennsylvania are stepping up their investigation of another roadway shooting that occurred eight hours earlier about 30 miles away.

Pennsylvania State Police, working with investigators from Maryland and the FBI, said Tuesday investigators say there are many similarities between the shootings. They say they’ll treat them as related until there’s conclusive evidence that they’re not.

Twenty-eight-year-old Timothy Davison was shot to death early Saturday after the driver of small pickup truck forced his vehicle off Interstate 81 a few miles north of the Maryland line.

On Friday night, on a local road in York County, police say someone in a black pickup truck fired shots into another vehicle. One bullet struck the driver’s headrest.

A police news conference scheduled for Tuesday morning was canceled.