Police are warning South Side businesses about three recent armed robberies in the Grand Crossing and Chatham neighborhoods.

In each incident, the robber walked into a store and pulled out a silver revolver before ordering a cashier to open the cash register, according to an alert from Chicago Police. During one of the robberies, the suspect leaned over and took money from the register.

The robber was seen driving off in a black or dark-colored vehicle with front-end damage and a spare tire on the passenger side, police said.

The robberies happened:

• about 7:15 p.m. Feb. 15 in the 7500 block of South Stony Island;

• about 8:20 p.m. Feb. 22 in the 400 block of East 79th Street; and

• at 8:26 p.m. Feb. 22 in the 1400 block of East 71st Street.

The robber is described as a black man with a dark complexion, thought to be between the ages of 40 and 60, standing between 5-foot-6 and 6-feet and weighing between 175 and 185 pounds, police said. He was seen wearing a blue skull cap during one of the robberies and a gray trapper hat during another.

Anyone with information about the robberies should call Area Central detectives at (312) 747-8380.