Stamford police released a surveillance video showing an armed robbery inside Stillwater Market that happened Monday night.

Store clerk Mohammad Shariff says the robbers pointed a knife at his brother-in-law and demanded cash. Once they were handed the money, Shariff says they asked to access the safe. When they were told that the store had no safe, the robbers took off.

Stamford police say Stillwater Market is the third store to be held up in a week. Lt. Tim Shaw, of the Stamford Police Department, says the robberies may be connected because the large knife used in the attacks has been described by eyewitnesses in similar terms.