MIFFLINBURG, Pa. (AP) -- Three Pennsylvania teenagers now stand charged as adults in a highway rock-throwing incident in Pennsylvania that left an Ohio teacher critically injured. Seventeen-year-old Milton resident Tyler Gregory Porter appeared in court Monday on charges including aggravated assault and conspiracy. Two other teens were previously arrested on those counts. Sunbury's The Daily Item newspaper reports a fourth participant has been charged as a juvenile. State police say the teens drove to an Interstate 80 overpass July 10 to throw rocks. One large rock blasted through a car windshield and hit 52-year-old Uniontown, Ohio, resident Sharon Budd in the face. She's in critical condition. Porter didn't have a lawyer for Monday's hearing. Court records say he told police another boy threw the rock that hit Budd's car.