A teenage girl was sexually assaulted while she walked to school Monday in southwest suburban Burbank.

The 14-year-old was on her way to St. Laurence High School about 7:40 a.m. when a man or teenage boy walked up behind her, threatened her with a gun and forced her into a nearby alley in the 7800 block of Central Avenue, according to a statement from Burbank police. He assaulted her in the alley behind a garage.

The suspect is between 17 and 20 years old, standing between 5-foot-9 and 5-foot-11 and weighing 150 to 170 pounds, police said. He was wearing a red or orange pullover hoodie, black pants and carrying a black backpack.

Police released stills from a nearby surveillance camera and are asking anyone with information to call investigators at 708-924-7300.

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