CHICAGO (CBS) – Two teenagers robbed 10 people, Monday night in one hour’s time in Chicago’s River North.

Mitch Bretall, bartender at 25 Degrees, witnessed this pair robbing one of the bar’s guests and shares his chase story with CBS 2’s Suzanne Le Mignot.

The pair, ages 14 and 15, started their armed robbery spree near Trump Tower.

The young men pulled a gun on victims saying, “don’t scream or I’ll kill you,” sources said.

The weapon was actually a BB gun.

The teens made their way north, entering 25 Degrees, 736 N Clark St. Bretall is a bartender there, who gave chase and helped stop this crime spree in River North.

“I saw a bunch of commotion,” Bretall said. “A lady’s complaining her phone just got stolen and she’s going out to chase the guy.”

Bretall gave chase too and as he was pursuing the suspects, they tried robbing someone else.

Eventually, Bretall followed both teens to 708 N. Dearborn, while his colleagues called 911.

As officers and Bretall closed in, one of the teens used a fire extinguisher to break a window. The teen then jumped through the window, onto the scaffolding and headed to the back of the building.

Bretall and officers jumped a fence, scaled equipment and then used the fire escape to get to the roof.

“By the time I got up there, we were both out of breath,” Bretall said.

The capturing of these two teens was a joint effort, Bretall said. “Well done on the police behalf, as well as our staff here.”

The teens are being charged as juveniles with aggravated robbery with a firearm and theft of cash of more than $500, police said. The reason for the gun charge is the victims had reason to think the offender had a real gun.