KARACHI- A private security guard was killed and two persons were injured today during an armed attack on a cash van in Karachi. According to police, the incident took place in Jahangirabad near Rizvia Society where four armed robbers on two motorbikes intercepted cash van of a private security company. Officials said the gunmen fired shots on the van in an attempt to stop it. However, they failed to loot the cash after the security guards returned fire. One of the guards received bullets in his abdomen and died on the spot whereas a brief crossfire between guards and bandits left two passersby injured. The robbers later managed to flee from the scene.