EDINBURGH city centre is at a standstill following a major criminal incident.

Around 50 police officers, some carrying riot shields and wearing balaclava masks, were dispatched to Cockburn Street in the city's historic Old Town.

The street was cordoned off, and sniffer dogs and fire engines were also on site.

Crowds gathered at around 10pm as police helicopters circled with area with spotlights.

Bystanders were told to keep back by officers on the scene.

Police also carried out a floor-by-floor search of the old Scotsman building.

On Twitter, one onlooker, Rudra Kapila, said: "Area is a mini war zone.'

Another bystander Abbie Jessie wrote: "All the streets have been blocked off by police and helicopters."

Police Scotland would not comment on speculation that there had been a shooting.

However, a spokesperson did confirm there was an 'on-going incident'.