Police issued a community alert Monday about a string of robberies in Grant Park and elsewhere in downtown Chicago in which unsuspecting victims had their chains or necklaces forcibly stolen.

In each incident, the robbers targeted lone victims on park property, and ripped away the gold chains or necklaces, police said.

The robberies happened at the following times and locations:

• Friday, Aug. 1, at 9:30 p.m., on Columbus Drive north of Roosevelt Road in Grant Park.
• Saturday, Aug. 2, at 9:45 p.m., on Balbo Drive between Michigan Avenue and Columbus Drive in Grant Park.
• Monday, Aug. 11, at 3:44 p.m., on Columbus Drive south of Jackson Drive in Grant Park.
• Wednesday, Aug. 13, at 5:25 p.m., on Wacker Drive east of Columbus Drive in the New Eastside area.
• Friday, Aug. 22, at 8:43 a.m., in the first block of East Wacker Drive downtown.
• Friday, Aug. 22, at 8:48 a.m., again in the first block of East Wacker Drive downtown.
• Friday, Aug. 22, at 11 a.m., in the 200 block of East Roosevelt Road in Grant Park.
• Friday, Aug. 29, at 4:12 p.m., on East Wacker Drive downtown.

The robbers are described as one to four men and women between the ages of 20 and 40, or one man wearing a black T-shirt, blue jeans, and white gym shoes.

Anyone with information should call Belmont Area detectives at 312-744-8263, or submit an anonymous tip at CPDTIP.com and use reference #P25-3-036A