EDITOR'S NOTE: The latest update on this story can be found here. Our original story continues below.
Police in Forest Park, Illinois, have released new details after four individuals were shot and killed on a Chicago Transit Authority Blue Line train Monday morning.
According to authorities, police received a 911 call after several individuals were shot onboard the train. Officers responded to the Forest Park station and cleared it of passengers before getting on the train, where they discovered four victims.
Three of the individuals were pronounced dead at the scene, and a fourth died a short time later at a local hospital.
Police have been examining surveillance footage, and it paints a disturbing picture of how the attack unfolded.
Authorities say the footage shows that the four victims were likely asleep in different parts of the train, and that all four were sitting separately as the attack occurred.
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Police also believe there were no fights or other confrontations on the surveillance footage. An eyewitness was identified via that footage, and police are working to track the individual down.
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The suspect in the case fled the train after the shooting, with police using surveillance footage to identify the individual. The suspect was later found onboard a CTA Pink Line train and was taken into custody. A weapon was also recovered, but it is unclear if it was the same gun used in the attacks.
While a motive has not been established, police say the shootings appear to be random in nature.
The CTA issued a statement on the attack Monday:
"Although this was an isolated incident, this heinous and egregious act of violence should never have occurred, none the less on a public transit train," the CTA said in a statement. "As soon as this matter was reported, CTA immediately deployed resources to assist the Forest Park Police in their investigation into the matter, including review of all possible security camera footage, which proved to be vital in aiding local enforcement. We commend both the Forest Park Police Department for their thorough and collaborative efforts to provide information to partner agencies; as well as the Chicago Police Department whose quick actions led to the apprehension of a suspect in this matter. CTA will continue to work with local law enforcement as part of this ongoing investigation."
More information is expected to emerge in coming days. Charges have not been filed, but the suspect remains in custody at this time.