4 killed in CTA Blue Line train station shooting near Chicago

Four people were killed in a shooting early Monday on a Chicago Transit Authority train in Forest Park, Illinois, officials said.

The Forest Park Police Department received a 911 call about three people shot on a westbound train at the CTA Blue Line station in Forest Park, just west of Chicago, around 5:30 a.m. local time, according to a statement from police.

Authorities cleared the station, finding four victims. Three were pronounced dead on scene and the fourth was taken to Loyola University Medical Center in Maywood, where they died.

Forest Park police, along with CTA security, used video surveillance to help identify the offender. Then the Chicago Police Department located a suspect who matched the description on a CTA Pink Line train. The subject was taken into custody and a firearm was found, Forest Park police said.

According to Forest Park officials, the shooting appears to have been an isolated incident with no immediate additional threat to the community.

In a statement, the CTA called the incident a "heinous and egregious act of violence" that "should never have occurred, none the less on a public transit train."

"As soon as it 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," the statement read.

The CTA commended the Forest Park Police Department and the Chicago Police Department for their rapid response and coordination.

CTA said it will continue to work with local law enforcement regarding the ongoing investigation.

This is a developing story. Please check back for updates.