CHICAGO (CBS) — Chicago Police on Monday night were warning anyone walking downtown or in the South Loop to stay alert after a series of attacks and robberies.

Investigators have linked those attacks and robberies to a group of teens. They have happened to people who have simply been walking down State Street and Michigan Avenue between Balbo Avenue and the Chicago River.

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And it does not matter if you are alone or in a group. Police said the youngsters are attacking and stealing from people at all hours.

On State Street near Van Buren Street, a woman waiting for a bus was surrounded by eight to nine teenagers overnight. They pulled out a BB gun and then beat the woman over the head with the pistol, leaving her hurt on the ground.

Over the weekend, a man and woman were ambushed by a group of teens in a robbery. That incident happened around 11:30 p.m. Saturday near State Street and Jackson Boulevard.

Police said a man and a woman were walking when a group of about nine people came up and demanded money. Several suspects then started beating the man and woman.

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The woman was left in critical condition in the hospital.

Another robbery was reported at 5:23 p.m. Sunday in the 100 block of East Balbo Drive off Michigan Avenue in Grant Park.

The assailants are described as being between 14 and 19 years old – both boys and girls. Police did arrest six suspects, but we are told there were up to 10 youngsters involved in the various attacks – and police fear others may try to do the same thing.

Thus, police have advised people to put down their cellphones and be alert and aware of their surroundings.

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Anyone with information is asked to call Area Three detectives at (312) 744-8263.