Adelaide CBD locked down in siege at convenience store

Adelaide's CBD was locked down overnight after a man allegedly threatened to shoot a convenience store worker, sparking a siege between him and heavily-armed police.

Elite Special Tasks and Rescue Group officers swarmed the area just before midnight.

Just before 11pm, a man allegedly walked into the CBD convenience store and claimed he was armed. He forced the shop attendant to call Triple Zero, before taking the phone from him and allegedly telling officers he had a gun.

"At the start I felt like it's not a big deal, but as things started to develop, it was terrifying," he told 9News.

When police arrived, the shop attendant fled.

CCTV shows police surrounding the back of the business.

The man was convinced to surrender after an hour.

Police found he was unarmed.

The 50-year-old, from New South Wales, was taken to Royal Adelaide Hospital.

He was charged with aggravated assault and property damage, and did not apply for bail during a bedside court hearing.

The shop franchise director told 9News he was considering how to prevent a similar incident from happening again, including the option of boosting security.