At least four students were killed and two others were injured Tuesday when their school van was caught in an exchange of fire between two groups in Orakzai agency, a private TV reported. According to reports, the ill-fated van was on its way to drop the students at their school when it was caught in an exchange of gun fire between two rival groups in Kalama Atman Khail area. Four students were killed on spot while two others were wounded who were rushed to Kalaya hospital, initial reports from the area said. Tension gripped the area after the incident while a local tribal lashkar has cordoned off the incident site, it was reported.