Police issued a warning this week to bikers and runners along Chicago's lakefront.
Officers said they saw an increase in robberies in November and December near the 4300 block of South Lake Shore Drive and are urging those who use the lakefront path to be extra alert.
"The victims have been approached and attempted to be engaged in conversation with the offenders," Sgt. Gregory Jackson said, "at which time the offender will physically wrestle down the victim and then take properties by force."
They said two men, possibly teenagers, rob their victims as they ride or jog by. It's not clear whether they carry weapons.
The suspects were described as two black men, ages 16 to 20, standing 5-foot-6 to six foot and wearing dark clothing. Two incidents occurred around 5:35 p.m. Dec. 2 and around 5:30 p.m. on Dec. 11.
Runners were warned back in September too when several people reported being attacked on the lakefront path by a roller blader who threw punches and elbows or grabbed them around Navy Pier and Monroe Harbor.
Anyone with information about the robberies is asked to call police at 312-747-8380.