According to the police, the incident took place near North Campus of Delhi University around 11 AM when custodians of the cash van, belonging to a private cash replenishment company, were in the process of refilling money into an ATM of a leading private bank at Bungalow Road.
"When the cash van reached near the ATM of Citibank, two unidentified bike-borne armed assailants arrived there and attacked its security guard. One of the accused shot at the guard for resisting their robbery attempt," a senior police official said.
Police said the accused also threatened to kill custodians of the cash van and escaped with a bag containing Rs 1.5 crore kept in the vehicle.
The security guard was rushed to a nearby hosptial where he was declared dead.
"We are scanning the footage of CCTV installed at nearby areas to ascertain the sequence of event. We are yet to ascertain the looted amount and further probe is on," he added.