The reservoir is a popular site for joggers, runners and people walking their dogs. Authorities say the suspects tend to strike in the evening hours, and they are going after people exercising with their headphones on.
Investigators say the thieves are stealing phones and iPods from the joggers. There have been two cases so far in the last two weeks, and in once case, investigators say the suspects brandished a weapon.
The suspects were described as three or four Hispanic males, ages 16-20, with black hair and brown eyes, 5 feet 8 inches tall to 6 feet tall, weighing between 160 and 200 pounds. They were last seen driving a silver or tan 1998-2000 Toyota or Honda with four doors, tinted windows and a square back.
If you have any information about these robberies, you're urged to contact Los Angeles Crime Stoppers at (800) 222-TIPS or (800) 222-8477.