A Port Huron man visiting a friend at a Fort Gratiot store was injured when both men mistook a man robbing the store as a friend playing a practical joke, police said.

Police said a masked man entered

brandished a handgun and demanded money.

Police said Patrick O’Bryan

walked up to the man, thinking he was a friend, and grabbed him in horseplay. The gunman hit O’Bryan in the head with the gun, and the clerk, Bryan Sandler

opened two cash registers and gave the man money.

The gunman took an undisclosed amount of cash and was last seen running south on Gratiot Avenue. O’Bryan was not seriously injured and did not seek medical treatment.

Store owner Howard Sandler said Wednesday’s incident was the first robbery at the store in its 150-year history.