An armed robber threatened Post Office staff and left one worker injured before escaping with cash.
Police were called to the Post Office on Blackburn Road in Astley Bridge just before 9am this morning.
It is understood staff were threatened with a 'bladed weapon'.
Police remained on the scene into the afternoon.
A spokesman for Greater Manchester Police said: "At around 8.55am this morning (Thursday 29 August 202), we were called to reports of a robbery at the Post Office on Blackburn Road, Bolton.
"It is believed that a man entered the premises and, after threatening staff with a bladed weapon, left with a sum of money.
"One staff member suffered minor injuries, no arrests have been made and enquiries are ongoing.
"Officers in Bolton are keen for anyone who witnessed the incident or who has information to call police on 0161 856 5591 quoting log number 707 of 29/08/2024.
"Information can also be reported online or by using the LiveChat function at www.gmp.police.uk. If you can't report online, call 101 or Crimestoppers anonymously on 0800 555 111."
A local worker in the area said: “There was a break-in earlier this morning and I saw the shop keepers in commotion.
“There was lots of disturbance and I saw someone exit around the back of the building.”
A Post Office spokesperson said: "We can confirm there was an armed robbery at Higher Blackburn Road Post Office on Thursday 29 August at 8.47am.
“We are supporting the operator of the branch, who is assisting the Police in their efforts. We would urge anyone with information to contact the police or Crimestoppers anonymously on 0800 555111.
“Higher Blackburn Road Post Office is temporarily closed. It is not yet known when the branch can re-open. We apologise to our customers for any inconvenience caused and thank them for their understanding. Alternative branches in the area include Halliwell Road, Castle Hill, Church Road and Haulgh. Please visit www.postoffice.co.uk/branchfinder for opening times and services offered.”