This is the moment masked men robbed Securicor guards in the middle of a busy shopping street.

Scores of shoppers in London Road, Brighton, watched as a woman guard was forced at gunpoint to sit on the pavement.

A cash bag, believed to contain thousands of pounds, was grabbed before the offenders fled.

No one was hurt but the guard was said to be badly shaken.

While she was being questioned by detectives her partner sat locked in the Securicor van before it was taken to John Street police station for examination.

Witnesses were shaken up. One told The Argus: "It was terrible - people were screaming that the man had a gun."

A young mother who gave her name as Julie said: "It was very frightening. I was pushing my 20-month-old baby in a buggy nearby when it happened.

"The two men had dark balaclavas on and I saw at least one gun. "The guard was sat on the pavement while they were trying to get something out of the back of the van. One of the robbers had a bag with him - then they fled.

"I was just out doing some shopping at the time and never expected to see anything like this."

Chief Inspector Lawrence Hobbs said the guards were making a delivery shortly after 11am yesterday when the robbers struck.

It is understood the cash was going to the nearby Abbey Bank. Joyce Millican, 50, who works at nearby Happit in London Road, said: "All we knew was that there were two men in balaclavas, one in black, one blue, who ran towards the security guards and held them on the ground at gunpoint.

"A customer was shouting 'gun'. One robber was 6ft, the other was smaller.

"After a lot of shouting they ran up the road and up a side street."

Another witness who preferred not to be named said: "I was walking down the road and just heard someone say, "give me your money" then they got down and I heard someone say 'gun' so I flew into the Happit shop."

Store detective Dan Cleaver, who works at Somerfield supermarket, opposite the robbery scene, was called to the scene but arrived too late to help.

He said: "I just saw the car driving away towards New England Street. Securicor comes every day but it hasn't happened here before."

Mr Hobbs said the offenders were thought to have run into nearby Ann Street and escaped in a red BMW.

He said: "We have a lot of witnesses but we would like to hear from anyone who saw what happened and, in particular, the men getting into the BMW."

Although "cash-in-transit" robberies are rare in Sussex, they are happening increasingly frequently.

There were three in 2004 and that number doubled last year. But there were three attacks on Securicor workers in February.

Union leaders have warned workers transporting large sums of cash are not receiving enough protection from the authorities.

Witnesses should call Brighton CID on 0845 6070999.