Between 12.15pm and 1.05pm on Saturday there were attempted robberies at Newton Longville Post Office and the Londis on Main Street, Grendon Underwood.
Newton Longville had an unknown person enter the post office at 12.15pm, they produced an object suspected to be a handgun and demanded items from the cashier but ran off without getting anything.
At 1.05pm someone matching the description from the previous robbery attempt tried to enter the Londis on Main Street but a staff member in the shop was suspicious of his behaviour and locked the doors before he could gain entry.
The offender is described as male, around 5ft10 inches and of a medium build. He was wearing dark clothing, clothes and a V for Vendetta face mask.
He made off in a Vauxhall Astra with mud covering the front and rear index plates.
Officers responded to this second incident and following a brief pursuit, the vehicle collided with street furniture in Winslow and four people were subsequently arrested. Nobody was injured.
Investigating officer Detective Sergeant Dale Price, of Aylesbury CID, said:
“I’m appealing for anybody who witnessed either incident on Saturday to please make contact with police.
“I’m particularly keen to hear from anyone who has dash-cam footage from the area to please check this and contact police if it has captured anything that can help this investigation.
“You can do so by making a report online or by calling 101, quoting reference number 43200168336.
“Alternatively, you can contact the independent charity Crimestoppers 100% anonymously on 0800 555 111.”