CHICAGO (CBS) — Surveillance video from an alley in Bucktown gives a clear look at what becomes a crime in progress.

The video sent to CBS 2 by a tipster shows two men walking in an alley, a couple crossing in front of them, and then one of the men pulling out a gun before following the couple around the corner.

Chicago police confirmed there was an armed robbery around 3:15 a.m. Wednesday near Damen and Charleston. Images from Google Maps confirm the surveillance video came from the same location.

While the video does not show the robbery itself, a police department spokesperson said investigators are reviewing the video to definitively link it to the robbery.

Police said a 25-year-old woman and a 31-year-old man were walking on the sidewalk when two men came up from behind and knocked them to the ground. One of the suspects hit the man in the back of the head with a pistol.

The suspects robbed the couple at gunpoint and ran south on Damen.

The male victim was treated at St. Mary’s Hospital for minor injuries.

No one was in custody Wednesday morning. Area North detectives were investigating.