A two-vehicle collision in Defiance County Thursday afternoon sent the Pro Medica air ambulance to the scene. The Defiance Post of the highway patrol reports that crash occurred at on state route 15, just south of Carter Road. 40 year old Anthony Silva of Defiance was northbound on route 15, when his vehicle drifted left-of-center, striking an oncoming semi driven by 45 year old Greg Otto of South Charleston, Ohio. Anthony Silva suffered serious injuries; and was taken from the scene by helicopter to the ToledoHospital. The truck driver was not injured, and both subjects were wearing seat belts.