CALGARY — A violent armed robbery at a convenience store has city police asking for help.

Around 2:40 a.m. Wednesday, a man walked into a store in the 6000 block of Memorial Drive N.E. He went up to the counter, pulled out a black handgun and pointed it at the victim, police said.

The robber demanded cash, but the worker refused.

The culprit walked behind the counter and hit the victim in the head with the gun, forcing him to the ground.

He then grabbed the register, and left out the front door, police said.

He’s a white man, 30 to 35 years old, five foot nine with a medium build. He was wearing a dark hoodie, jeans and white shoes.

Police have released surveillance video from the incident.