MASKED raiders wielding a terrifying array of weapons escaped with £37,500 after three separate armed robberies.

The gangs struck across Bolton in the space of two hours as cash deliveries were being made to a petrol station, a post office and a bank yesterday.

The biggest haul was from Johnson Fold Post Office in Moss Bank Way where two men brandishing a handgun escaped with £27,500.

Two robbers riding a powerful motorbike and armed with a machete, fled with £10,000 from a security guard outside Lloyds TSB in Market Street, Farnworth.

And a security guard was slashed across his wrist arm as he struggled with two masked men carrying a machete and a sledgehammer on the forecourt of the Shell petrol station in Bridgeman Place in Bolton town centre.

They fled with a cash box - but it was empty.

Police said they had no cause to immediately link the robberies, but described the violent attack on the guard as a "worrying development".

"We're appealing to members of the public to help us with information which could help to catch these offenders who have shown today that they are willing to threaten and use violence as a means of taking large sums of cash," Det Insp Paul Hitchen, of Bolton CID, said.

The first of the three raids took place at 11.20am when a Securitas guard was delivering money to a cash machine on the forecourt of the Shell petrol station.

Two men, both wearing balaclavas, threatened the guard with a machete and sledgehammer before one of the attackers lashed out with the machete, slashing the guard across his right wrist and left upper arm and causing him to drop a cash box.

The men then sped off in a stolen red Peugeot 307, registration number KW51 RVM, which was later found dumped in an alleyway behind Bromwich Street inThe Haulgh.

The raider had tried to set it alight.

Detectives later revealed the cash box they had taken had been empty.

The guard was treated at the Royal Bolton Hospitalfor a deep wound to his wrist.

The next raid took place at 11.22am, just two minutes after the petrol station raid.

Two masked men, one armed with a handgun, burst into Johnson Fold Post Office. A cash delivery had just been made to the branch by a Royal Mail liveried van.

One of the men pointed the gun at a member of staff who handed over money, believed to be £27,500 in cash.

The robbers then ran off through the back of the shop and escaped down a back alley.

Yesterday's robbery was the third at the branch in the last 11 months.

An robber armed with a kitchen knife vaulted the counter and fled with cash in February. In Decemberf, two men carrying a handgun threatened teenage counter staff and escaped with £50,000.

In the third raid yesterday, at 1.06pm, two robbers grabbed £10,000 from two guards employed byG4S, formerly Securicor, who were delivering money to the Lloyds TSB bank in Market Street, Farnworth.

The men pulled up at the scene on a high-powered Honda Fireblade motorbike and one threatened a guard with a machete before they rode off in the direction of Kearsley with a cash box containing an estimated £10,000.

The branch was targeted just five weeks ago in a similar robbery, which saw masked men armed with an iron bar escape with £20,000 after threatening a guard outside the bank.

Det Insp Hitchen said: "There is a trend for armed robbers to use machetes and similar weapons for cash-in-transit robberies and one of today's attacks has shown that some are prepared to use them."

He sais that the guard attacked at the petrol station had suffered deep cuts and all those caught up in yesterday's robberies had been left shaken.

"We would appeal for anybody with information, particularly about the movements of any of the vehicles, to come forward," he said.

CCTV tapes are being examined by detectives investigating the robberies.

Anybody with information is asked to contact Bolton CID on 0161 856 5740 or Crimestoppers anonymously on 0800 555 111.