The new safety apprehensions followed two separate disturbances over the weekend on Michigan Avenue and at a nearby CTA Red Line station.
Police say the two incidents are unrelated. They refer to them as "wildings," in which large numbers of teenagers come downtown to cause trouble.
A total of 28 arrests were made Saturday evening.
As the weather begins to get warmer, residents and business owners alike are wondering what this might mean for the future of Michigan Avenue.
Many say the incidents are portraying a bad image of the city.
Some small businesses just off Michigan Avenue are worried about the impact these disturbances could have on their bottom line.
"It may deter people from coming downtown. Who's going to want to come downtown to an area that is unsafe. Nobody. And it definitely affects small businesses like our textbook store," said Beck's Bookstore's Keyna Baker. "We definitely don't want this kind of activity, because it does deter customers from coming down."
At a press conference Monday morning, Police Superintendent Garry McCarthy and Mayor Rahm Emanuel defended their response to the disturbances Saturday, during which large groups of teenagers allegedly bumped into other people, blocked sidewalks and traffic, and started fights among themselves.
"We're doing our jobs, and the strategy downtown is high-profile visibility and enforcement where appropriate," said McCarthy.
Meanwhile, at the Chicago Red Line station, which is viewed as the main vehicle for those participating in these flash mobs, members of the Guardian Angels patrolled the area Monday hoping to serve as a deterrent for those looking to cause trouble.
"It's important we get an early start, as opposed to waiting until the weather gets warmer," said Guardian Angels' Miguel Fuentes. "We have a lot of events coming up. We have Lollapalooza. We have Taste of Chicago around the corner. We have to nip this in the bud. . . First and foremost the Red Line which is the main vehicle people are using to get in and out of the areas the flash mobs are happening."
Emanuel says the city has increased police presence near Michigan Avenue to respond to any incident.
"Every night there ire additional officers in that area," said Emanuel.
Still, some Chicagoans say they continue to fear for their safety.
"Years ago I wasn't afraid to walk around in this area, but I'm definitely much more careful downtown than I used to be," said Susan Melner.