Detectives are investigating three incidents at post offices and stores in the Wigan and Leigh area - including one where a worker was threatened with an axe by a man in a clown mask.
An intruder burst into Abram Post Office, in Warrington Road, on Tuesday August 1, according to police in Leigh, armed with the weapon and issuing several threats.
An investigation is now understood to be under way after the axeman fled from the shop without taking anything.
A Leigh Police spokesman said: “(The) thief threatened a lone worker, who bravely protected the post office. The would-be thief took flight empty-handed.”
The branch, at the corner of Kingsdown Road, is part of Village News. No description of the raider has been issued so far by police, who have initially treated the incident as an aggravated burglary.
The owner of the store declined to comment, when contacted by the Wigan Post, but confirmed that he was assisting police with their enquiries.
Armed raiders have pinpointed the post office at least three times now over the past decade.
Two men were given indeterminate jail sentences at Liverpool Crown Court in 2008 for their roles in a gunpoint raid on the premises.
And axe-wielding men were also held responsible for a robbery there in 2012, when a pair jumped over the counter and threatened staff, before fleeing in a car towards the East Lancs Road at Golborne.
Another inquiry is also under way after two men carried out a robbery at a newsagents and post office in Lowton on Sunday, July 30.
The masked pair are said to have targeted McColl’s, in Newton Road, at around 3.30pm. A Greater Manchester Police spokesman said: “Two men have gone into the store, with their faces covered, and it is believed that they were armed.
“They have escaped with cash from the till and it looks like they have ran out of the shop.
“No-one was injured as a result of the incident.”
A few hours later at around 10.50pm, police were called to reports of another armed robbery at the McColls Store on Atherton Road in Hindley.
This robbery involved two men who jumped over the store counter and threatened the shop assistant with a knife.
Terrified, the assistant opened the cash register and the two men ran off with the till’s contents in an unknown direction.
Police have released CCTV images of men they wish to speak to in connection with the investigation.
Detective Constable Jessica Samouelle of GMP’s Wigan Borough, said: “The assistants at these McColls stores have been left in shock after being threatened with weapons to open the stores’ tills.
“I can only hope that someone recognises the men in the images, in order to help with our investigation.
“I’m urging anyone who was in either Hindley or Lowton at the time and saw anything or know the men in the images, to please come forward.”
Anyone with information should contact police on 0161 856 7331 or 101 quoting incident number 1386 of 30/07/17, or the independent charity Crimestoppers on 0800 555 111.