By Suzanne Le Mignot

(CBS) — They are young  and armed — thieves on the prowl. Their target? Salons and massage spas in Chicago.

As CBS 2’s Suzanne Le Mignot reports, surveillance video is proving quite helpful.

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Two teens, wearing hoods, enter Happy Feet massage spa in Norwood Park. They go straight to the front desk and start taking money. The receptionist calls out for the owner. When she enters the room, one of the teens pulls a gun on her.

“I say, ‘OK. You can take everything,’” the owner tells CBS 2’s Suzanne Le Mignot. “I’m so scared.”

After holding the owner at gunpoint, one of the teens enters the back laundry room and takes money from a purse. He heads to the front, with a worker’s bag in hand. Then, both teens leave.

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Sources say the armed robbery inside Happy Feet massage spa was one of about a dozen that took place in Chicago in just the past month.

Chicago isn’t alone. Similar crimes committed by teens have occurred in Northbrook, Gurnee, Highland Park and Waukegan.

In some cases, there have been two people who enter. In others, as many as seven have swarmed business, robbing workers and sometimes customers.

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Police in Gurnee and Northbrook say they’ve arrested a total of four suspects so far. Chicago police say detectives are looking at patterns in the cases.

Suzanne Le Mignot