Lt Col Somprasong Rabaisa-ard of the Patong Police was called to the scene at about 12:15am.
At the scene, store staffer Suphanee Waelae, who was still in shock, told police that a man entered the shop at 00.03am. He was wearing a full face mask, black sweatshirt, jeans and black flip-flops.
The was carrying a foldable knife, and placed a piece of paper on the cashier counter, she said.
Ms Suphanee explained that the man walked behind the counter and ordered her to open the cash register.
As seen in the store’s security CCTV footage, the man first had Ms Suphanee open one cash register, then another.
Attempts to open the third cash register failed, prompting the robber to attempt to open the cash drawers under the cash registers behind the counter. Those attempts also failed.
Satisfied that he had exhausted his options, the robber then walked calmly out of the store.
Throughout the CCTV footage, the robber seemed familiar with operating the store’s cash registers, at times using the touchscreen to enter commands himself.
The man wore gloves throughout the robbery.
After the robber had left the store, Ms Suphanee waited cautiously to be sure that he would not return before she called 191.
The man made off with about B3,000 cash, police reported.
Lt Col Somprasong explained that this morning Patong Police Chief Col Aganit Danpitaksat held a meeting and ordered all police to find the robber as soon as possible.
At this stage, police are still investigating by checking CCTV footage from the nearby cameras to try to identify the route that the robber used to flee, and are questioning staff and people living nearby, Lt Col Somprasong said.