CHICAGO, Ill. -

A missing Waukesha County teen has been found alive in Chicago.

Investigators said Kathryn Stalbaum was found safe in Chicago. Waukesha County Special Investigator Eric Severson said in a press conference Friday night, Stalbaum approached a Chicago police officer and asked for help.

Severson added why Stalbaum vanished and how it happened are unknown. Stalbaum reportedly went up to a police officer in Chicago Friday and said she needed help. He said authorities acted quickly. 

According to Severson, Stalbaum is safe and has spoken with her family. He said "they were elated" to hear her voice. 

She was reported missing Tuesday. According to the Waukesha County Sheriff's office, Stalbaum missed the bus and texted a friend she would be biking to school. She never showed up. 

Thursday, deputies found Stalbaum's bike nearly 8 miles from Kettle Moraine, the high school she attends in Waukesha County. They said no signs of foul play were suggested at the scene.