Railroaded!

Railroaded is a 1947 blackandwhite film noir directed by Anthony Mann, and starring John Ireland, Sheila Ryan, Hugh Beaumont and Jane Randolph.

Clara Calhoun is a beautician with a shop in New York. Her shop is in fact a front for a bookmaking operation. One evening when she closes up for the night, she gives a silent signal to two masked gunmen lurking outside. These two bandits then burst into the shop and hold up both Clara and her unsuspecting assistant, Marie Westin. The money they get hold of is betting money from the illegal operation.During the robbery, a policeman just happens to be in the neighborhood. He sees the hold up and tries to interrupt the robbery. When the policeman intervenes, one of the robbers, Duke Martin, shoots him down with his gun. Before drawing his last breath, the police officer manages to shoot and wound the other robber, Cowie Kowalski. The two robbers then escape the scene in a laundry truck, and Duke drops off Cowie at a doctors house for medical care. Before leaving Duke reminds Cowie of the plan to implicate a certain Steve Ryan in the crime. ........

Source: Wikipedia