CHICAGO (CBS) — Chicago Police have warned holiday shoppers to be on the lookout for pickpockets, and have offered tips on how to avoid becoming a victim.

“Avoid crowding a bus or train doors. Pickpockets take advantage of crowds, and usually work in teams of two to four. Pay particular attention to body contact, such as bumps,” said Public Transportation Unit Police Cmdr. Cindy Sam.

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The commander said a common tactic is to create a pileup while waiting to get on a train or elevator, or going through a revolving door.

“Criminals like to take advantage of crowds. So if there’s a crowd, and you’re not aware of your surroundings, you make yourself vulnerable,” she said.

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Sam said pickpockets also use distraction to relieve people of valuables.

Officers at the Central District station in the South Loop demonstrated different scenarios, including a woman approaching a man using a tablet computer and asking him for directions. While the man looked away from his tablet to a the woman’s map, another woman walked off with the device.

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Sam suggested not wearing headphones in a crowd, and to avoid focusing too much on your smartphone. She also said people should lock their valuables in their trunk after parking their cars.