A GANG of robbers attacked a security guard in front of terrified shoppers at Tesco in broad daylight.

The incident took place on Monday as a security guard from G4S filled up the cash machine outside the store, in Brighton Road, Purley, at about 1pm.

Witnesses described seeing robbers grappling with the guard as they tried to steal the cash.

A woman, who saw what happened as she parked her car, said: "The G4S man was trying to explain to them that all the money was locked away and he could not get to it.

"I have never been so terrified. I didn't know what to do."

Another eyewitness, who was waiting to withdraw money, said: "It all happened so fast and no one could quite believe it."

According to witnesses, the robbers grabbed a cash box before piling into a silver Renault Clio and speeding away.

A high-speed chase involving police cars and a helicopter ensued.

A police spokesman said the Clio collided with another car on the A236 Southbridge Road, but no one was hurt. The suspects then swung into Surrey Street market in the heart of Croydon.

Trader Russell Smith, 49, described seeing the car "screeching" around the corner before colliding with another vehicle.

"They started bailing halfway down (the road) and then there was a loud bang," he added. "At that point they did bail out and scattered."

Abdul Rehman, 17, said he was at his stall when he heard sirens.

"It seemed like there were police and ambulances coming inside the market," he added.

"Then I saw the car, and we were shocked because cars are not allowed in the market."

A cash box was recovered in Surrey Street but police have not confirmed whether or not the suspects escaped with any money.

Two suspects were arrested after the incident.

On Tuesday, a 24-year-old man, of no fixed abode, was charged with robbery. He appeared at Tower Bridge Magistrates' Court on Wednesday and did not enter a plea. He was remanded in custody until his next appearance at the Old Bailey. A date has yet to be set.

A 17-year-old boy was also arrested after the incident and released on police bail, pending further inquiries.

It is believed a third suspect may still be at large.