PHOENIX, Ariz. - Arizona authorities confirm that 11 vehicles have been shot at in the Phoenix area, most occurring on freeways in a string of incidents that have put residents on edge.

Arizona state police say they can't confirm that shots were fired from one vehicle at another on a Phoenix freeway Friday morning.

Department of Public Safety spokesman Raul Garcia says the latest shooting involved a commercial truck. Its driver on Thursday reported finding a bullet hole in the cargo area after hours of making deliveries.

DPS previously listed 10 other incidents involving vehicles on freeways getting hit with gunfire or other projectiles in the last two weeks. There have been no serious injuries, but the shootings have left the city on edge and some drivers searching for alternate routes. 

Investigators also are examining a tractor-trailer near Interstate 10. Garcia says it hasn't been determined whether the vehicle was shot at. A car window was damaged in a third incident Thursday, but Garcia says it doesn't appear it was a shooting.