UPDATE [9/30/2013, 11:24 a.m. EDT]: CBS Chicago reported that police are investigating if the CTA train was hijacked before it crashed into an out-of-service train. Suspicions of a hijack were raised because the train had only four cars, which is atypical for a rush hour commute. Forest Park Mayor Anthony Calderone added that no one was at the controls during the crash, but the CTA did not confirm.

-

Nearly 50 people were hospitalized on Monday morning after a Chicago Transit Authority (CTA) train collided head-on with stopped train.

According to The Chicago Tribune, the accident happened at 8 a.m. Monday morning when an outbound Blue Line train hit an out-of-service train going the opposite direction. CTA spokeswoman Lambrini Lukidis confirmed the details of the crash at the Harlem station, but officials are investigating why the stopped train was on the track.

Forest Park Mayor Anthony Calderone told The Chicago Tribune that 48 people were taken to 10 hospitals, none with serious injuries. Loyola University Medical Center told NBC Chicago that four patients arrived from the crash but their injuries were "not serious.”

It is unclear how many people were on the train during the crash, but Lukidis said there were no passengers on the out-of-service train. Lukidis said officials do not know how many workers were on the stopped train.

The Chicago Tribune reported that onlookers heard the crash and screams, with one person allegedly yelling, "Stop! Stop! Stop the train!” according to witness Taylor Pettiford.

"I instantly started crying and I called my mom to come pick me up," 17-year-old Pettiford said, adding she was rushed off the platform by the CTA.