Merseyside Police detectives are appealing for information following a robbery which took place at a petrol station in Vauxhall on Monday 11 April.
At around 2.10pm a man approached a security guard leaving the Spar store and garage on Great Howard Street and pointed what is believed to be a handgun at him.
He then took a cash box from the security guard and made off in a black BMW 3-series car, which had rear tinted windows, and which was parked on the forecourt.
The security guard was not injured but left badly shaken by his ordeal.
Merseyside Police said an investigation into the incident is ongoing and CCTV and forensic opportunities are being explored.
The male offender is described as around 5ft 11 in tall and wearing a grey tracksuit with an orange high-vis jacket and balaclava.
Detective chief inspector Mark Tivendale said: “This happened in the middle of the day and I believe the area around the petrol station and Great Howard Street would have been very busy with passing traffic.
“We would appeal to anyone who witnessed the incident or saw the BMW either before it drove onto the garage forecourt, or following the incident to contact us.
“Thankfully the security guard was not injured during the incident but I want to reassure members of the public that we will do everything we can to find the person responsible.”
Anyone with any information is asked to contact Merseyside Police on 0151 777 8617 or the confidential Crimestoppers line on 0800 555111.