CHICAGO (CBS) — Police are trying to determine if the same people are behind six violent robberies in Lakeview and Lincoln Park.

Two robberies happened on the same night, less than a block apart.

Police issued a community alert for the two robberies that happened Wednesday night around 11:45 p.m. – one on the 3700 block of North Marshfield, and the other on the 1600 block of West Waveland.

Sources said a pizza delivery driver was pistol-whipped and robbed near Marshfield and Waveland.

Not long after that, a 17-year-old boy was walking near Waveland and Ashland, when a man with a gun hit him in the back of the head and robbed him. The victim suffered minor injuries.

The suspect, who was wearing a red baseball cap and long-sleeve button-down shirt – got away with the teen’s cell phone and wallet.

The suspect matches a similar description of one of three men who robbed a nearby restaurant on Monday. Police said three gunmen wearing ski masks forced six members of the waitstaff at Tuco and Blondie to lie on the floor, while taking managers into an office of the restaurant at Roscoe and Southport, less than a mile away from Wednesday’s robberies.

The robbers pistol-whipped the managers, and then took cash from the safe and money box, along with five cell phones from the employees.

Police have said that trio is suspected of three other robberies in Lakeview and Lincoln Park between July 26 and July 29.

Detectives are now investigating whether all six of the robberies were connected.