QUETTA- One assailant was killed in retaliatory firing by policemen while two others managed to escape in Quetta as some unidentified armed men attacked police mobile van today. According to the police, some unknown gunmen riding motorcycles opened fire at a police van in Qambrani Road in Quetta. During an exchange of fire, one attacker was injured while two others riding motorbikes escaped from the site. The injured was taken to hospital where he succumbed to injuries. The body was sent for autopsy. The police personnel remained unhurt in the incident. Meanwhile, the police personnel conducted search operation to arrest the other two assailants. A pistol and a motorbike were seized in the search operation.