Police in Concord are investigating after they said a gas station clerk was put in handcuffs by a man robbing the store.Concord police said the burglary happened early Tuesday morning at a Shell gas station. Investigators said the man was caught on security camera stealing cigarettes and scratch tickets. The robber was described as a white man about 6 feet tall with a medium build. He was wearing a black Carhartt jacket and a face mask. Police said the robber did not appear to show a weapon, but that's under investigation. It's also unclear what the robber said the clerk.>> Download the free WMUR app to get updates on the go: Apple | Google Play <<"An unknown assailant had come into the establishment, put him in handcuffs, took him outside the store, placed what we believe was a pillowcase over his head," said Deputy Chief John Thomas.Eventually, the clerk was able to break free to flag down a passing police officer."I would say that he was very startled,” Deputy Chief Thomas said. “That obviously doesn't happen all the time on his shift. Any time when any sort of violence like this occurs, I think anybody in that situation would be terrified, and this individual was very terrified with what occurred." Investigators said the robber was able to get away before police got to the area."We are following up on some leads as we speak, but it is still early in the investigation," the Deputy Chief said. Anyone with information is urged to contact Concord Police.