Police said that Rox, Mappin and Webb, Laing the jeweller and Lewis Grant were targeted by men, with a small quantity of jewellery being taken from Rox.

Officers believe a white VW Golf, which has been recovered in St James Road, Townhead, was used as a getaway car in the robbery.

In a statement, Police Scotland said: "Officers are carrying out enquiries and appealing for information following a robbery in Glasgow city centre today.

"Around 12.50pm today, police were called to a report of four jewellers - Rox, Mappin and Webb, Laing the Jeweller, Lewis Grant - being targeted by four males. They managed to enter only one of the jewellers - Rox - and quickly grabbed a small quantity of jewellery before running off.

"A security guard sustained a leg injury during the incident. The four male suspects were last seen running up a lane at the side of the arcade's Buchanan Street entrance.

"Officers are currently speaking to witnesses and gathering CCTV images to establish more details on the four men responsible.

"The four suspects are described as 5ft 8ins in height and of slim build. All were wearing dark clothing. It is believed that they made off in a white hatchback vehicle. A white Volkswagon Golf has been recovered in St James Road, Townhead, Glasgow and enquiries are also ongoing at that location to establish if it is the vehicle involved.

"Anyone with information is asked to contact Police Scotland on 101. Alternatively Criumestoppers can be contacted on 0800 555 111, where anonymity can be maintained."

Both uniformed and plain-clothed officers were at the scene at around 1.30pm today.

Eyewitnesses described seeing a gang - wearing balaclavas - running from Argyll Arcade in Buchanan Street with weapons and carrying holdalls.

Shutters were pulled down on the jewellery district, but officers could be seen taken statements from shaken customers and members of staff.

A lane next to the arcade - opposite House of Frasers - was sealed off with several police officers standing guard.

Video by David McCourt

Fire crews were also in attendance amid reports smoke could be seen coming from the arcade.

Video footage surfaced on social media of four masked people emerging from the famous mall onto Buchanan Street, apparently carrying sledgehammers.

Another video suggested that some form of smoke canister had been let off inside the arcade.

David McCourt, who took the video above, said: "Myself and two colleagues were walking up Buchanan Street when we were alerted by what sounded like a fire alarm coming from the Argyll Arcade.

"As we passed the opening to the arcade, we noticed many terrified looking shoppers fleeing from the scene.

"As we looked in, we noticed the arcade's smoke clouds had been activated with four to five figures dressed in black emerging.

"They were wearing balaclavas and began to charge at the security brandishing baseball bats and hatchets, with some of them attempting to break the reinforced glass as they began their escape.

"Unable to successfully make away with any merchandise, the group of thieves then fled, with one of them shouting "I'll f***ing kill you all", at which point I stopped filming.

"They were last seen disappearing down the adjoining alleyway on foot, witnessed by some 30 to 40 onlookers."

One eyewitness Ann-Marie tweeted: "Got screamed at off four balaclavad men at Argyll Arcade they would shoot me if I didn't move."

Calum Macaulay also tweeted, "Was about to enter Fraser's on Buchanan St earlier and alarms going off and blokes in balaclavas running from jewellery heist."