A man armed with a gun tried to rob four shops in Bradford yesterday.
Just after 3pm, he went into a post office on Wrose Road with what was believed to be a handgun.
He demanded money from staff at the counter but fled empty-handed towards Carr Lane after staff said they would call police.
At 6.30pm, another post office was targeted, this time on Lillycroft Road, where a man made demands for cash and threatened staff.
He was confronted by the staff member and again left empty-handed.
It is thought he was joined by two other men outside.
The third attempt took place at a food store on Bishop Street at 6.45pm where a similar approach was made to staff by a man with a suspected firearm.
Again the suspect made away without the contents of the till and along Bishop Street in the direction of Park View Road.
A further offence occurred at Subway on Keighley Road in Frizinghall just before 7pm. Threats were again made with what appeared to be handgun and demands made for money. The man subsequently left the shop.
The suspect described on each occasion is said to be in his late teens, of slim build, between 5ft 5ins and 5ft 11ins tall, wearing a grey jacket and a balaclava or face covering.
Detective Inspector Mark Long said: “Through the very nature of these incidents, their location and their timings, we are currently considering the links between each of them.
“Although there was nobody injured during these offences and nothing was taken, they are clearly extremely concerning.
“The victims in each offence will undoubtedly have been very frightened and fearing for their personal safety.
“We are currently conducting CCTV enquiries in each of the areas and detectives are working hard to ascertain the identity of those responsible.
“Such behaviour will not be tolerated in the District, particularly involving the use of a potential firearm.
“I would call upon any witnesses or anyone with any information which could assist our enquiries to come forward immediately.
“You can call Crimestoppers anonymously on 08000 555 111 or the non emergency number 101.”