At least three adults were killed and 60 high-school students were injured Tuesday when an 18-wheel truck crashed into a school bus in Mississippi. The head-on collision occurred near the intersection of state roads 8 and 9, just north of Calhoun City, in north central Mississippi. Calhoun County Coroner Jerry Fleming said a male bus driver and a female teacher on the bus were killed, as was the driver of the tractor trailer. The volunteer fire department was assessing injuries of the students, one of whom was airlifted to a local hospital. The students were seniors at Ackerman High School and were returning from a field trip to the University of Mississippi at Oxford.