NEW : Witnesses tell CNN they saw gunmen carry AK-47s , travel in a Jetta . Ciudad Juarez is across the border from El Paso , Texas , and has been the scene of some of Mexico 's worst violence in recent years . Man shot , killed in front of students at school in Ciudad Juarez ; 4 others injured . The Mexican government has said it will investigate the shooting and is working with U.S. officials to determine what happened. No students were injured in the attack ; suspects still on the loose .
NEW : Witnesses tell CNN they saw gunmen carry AK-47s , travel in a Jetta . Man shot , killed in front of students at school in Ciudad Juarez ; 4 others injured . The Mexican government has said it will investigate the shooting and is working with U.S. officials to determine what happened. No students were injured in the attack ; suspects still on the loose .