A security guard was shot dead and another wounded during a cash-in-transit heist in East London on Monday morning.

The Hawks in the Eastern Cape said a Fidelity cash-in-transit vehicle was allegedly collecting cash from Kausers Cash and Carry in Buffalo Street when the incident happened.

Hawks spokesperson Warrant Officer Ndiphiwe Mhlakuvana said there were three security guards inside the armoured vehicle, one of the security guards reportedly went inside the shop to collect cash.

Mhlakuvana said the security guard went out of the shop carrying cash in an orange money bag, intending to load it inside the cash truck, as the other guard was on standby next to the truck.

"While opening the cash truck, the security guards were ostensibly ambushed by four unknown armed suspects, who were driving a silver grey Hyundai. According to the reports, an undisclosed amount of cash was taken," said Mhlakuvana.

He added that a 44-year-old security guard was declared dead on the scene, while the other sustained injuries and was taken for medical treatment.

When News24 visited the scene, a large section of Buffalo Street was cordoned off while investigators combed the scene for clues.

An eyewitness, who works at a nearby retail shop, told News24 she heard four gunshots.

"One of them was wearing a blue overall, like the construction workers. It was so horrific witnessing them ambushing those security guards. One of them with a big gun was literally standing not far from our shop, but as soon as they were able to overpower the guards, he went to join them," said the eyewitness.