The robbery took place outside Tesco Express on Kilnhouse Lane, St Annes, as a male courier carried a cash box from the store to a van waiting outside.

He was accosted by three masked robbers who threatened to beat him up unless he handed over the money.

When he resisted, one of the thugs produced a silver machete and brandished the weapon in his face until he handed the cash over.

The men fled in a silver Mercedes car, driven by a fourth man, which they dumped on nearby Mellings Lane when the raiders got into a white van in which they escaped.

The guard suffered minor injuries during the attack.

Police are not releasing details of how much cash was stolen.

Neighbours told of their shock over the drama on their doorsteps, which happened just after 1pm yesterday.

One resident, who asked not to be identified, said: "I heard a car tyre screeching in the car park outside the shop. I ran out and saw a car speeding off so I took the licence plate number down and went back inside to phone the police.

"They must have been watching the shop beforehand because the security van doesn't come at the same time, it comes at a different time of day every visit.

"I've spoken to the police and told them what I saw. I just hope they catch them."

Another neighbour said: "I heard some shouting and then a load of car tyres screeching but didn't actually see them being robbed. I've told the police what I know."

Another neighbour from a house nearby said: "I usually sit out in my garden when it's nice like today but I wasn't outside when this happened.It had been a nice, quiet day.

"Since the police have been here the helicopter has been circling around looking for whoever's responsible."

A spokesman from G4S Cash Services (UK) said: "We can confirm that one of our couriers suffered minor injuries in this attack.

"We are committed to maintaining the safety of our staff and the general public."

Det Chief Insp Andy Webster, of Blackpool CID, said: "I want to speak to anyone who saw the robbery or noticed anybody acting strangely around the Kilnhouse Lane area either yesterday, or in the days leading up to the incident.

"We are also keen to identify where the car and its occupants have been before, during and after the offence. "

Anybody with information can contact Blackpool Police on (01253) 293933 or Crimestoppers on 0800 555111.