Police are investigating four robberies in an area southeast of Wrigley Field.
Police say that it is rather unusual for robbers to use pepper spray on victims. Usually it is the other way around.
However, the spray has been catching victims off-guard, and police are trying to get the word out for residents to be on the lookout.
Many residents in the East Lakeview neighborhood Friday night were aware of the recent string of armed robberies.
Police say four incidents in the last three days seem to be related, in that the suspects used pepper spray to stun the victims.
"The people are approached from behind. They hear footsteps. They get sprayed. Most of them have been knocked to the ground, maybe roughed up a little bit, their stuff taken," said Chicago Police Sgt. Tim Kusinski.
Police say there are two suspects, but so far, they have only a vague description. The attackers have generally stolen purses, wallets, and cell phones.
The victims have all been neighborhood residents walking alone in the overnight hours.
"I'm not the fearful type, but it still makes me, like, wary," said resident Maureen Davey.
Alderman Tom Tunney has sent a letter warning residents and suggesting they be extra careful walking at night. If possible, they are advised to walk in groups and in well-lit areas, to be aware of their surroundings at all times, and to try not to be distracted by cell phones or iPods.
Police say that pepper spray can be dangerous.
"You're not able to see. Some people have a hard time breathing. It just disables them for at least a few minutes," said Kusinski.
Police say the attacks have all happened between 1 a.m. and 3:30 a.m. Most of the victims have been women. The descriptions so far have been too general for police to be able to put together a sketch.