Chicago police on Monday were investigating a string of armed robberies that happened over the past week on Chicago's South Side.

Police said in each instance, two to four robbers exited a white sedan, approached the victims, and demanded their personal items at gunpoint.

In one incident, the robbers forced the victim into the car and demanded access to the victim's bank account.

The incidents happened at the following times and locations:

• Wednesday, Dec. 31, at 3:15 a.m., in the 5700 block of South Michigan Avenue, Washington Park.
• Wednesday, Dec. 31, at 3:30 a.m., in the 5200 block of South Michigan Avenue, Washington Park.
• Sunday, Jan. 4, in the first block of West 59th Street, Washington Park.
• Sunday, Jan. 4, in the 6100 block of South Langley Avenue, West Woodlawn.

The robbers are described as boys or men between the ages of 17 and 24, wearing black hooded sweat shirts and ski asks.

Anyone with information is asked to call Wentworth Area detectives at 312-747-8380, or to submit an anonymous tip at CPDTIP.com and use reference # P26-1-001 A.