COCHISE COUNTY — A 4-year-old boy was killed on Monday evening in a traffic accident near Pearce, state highway patrol investigators said.

According to preliminary reports, the two-vehicle crash — which involved a cow — occurred at 7:05 p.m. on U.S. Route 191 at milepost 37, said Arizona Department of Public Safety spokesman Bart Graves.

The driver of a vehicle was heading south on 191 when the motorist struck a cow, Graves said. The impact prompted the motorist to veer into the north lane and crash into another car. The youngster was a passenger in the northbound vehicle, Graves said, and the child suffered serious injuries.

The victim was taken to a Tucson hospital and was pronounced dead, Graves said.

This is a developing story. More information will be added as soon as it becomes available.