Aaron M. Sprecher/AP/File
An elevated train moves along the tracks on August 16, 2024, in Chicago.
CNN  — 

Four people who appeared to be sleeping on a Chicago transit train were fatally shot Monday morning, and a suspect has been taken into custody, police said.

“The victims, they were all passengers on the train early this morning,” said Forest Park Deputy Chief Chris Chin. “The train was in motion on the way into Forest Park.”

The victims may have been homeless, Chin told CNN. Investigators are working with the Chicago Transit Authority to review surveillance footage of the shooting, which police said happened in two train cars: three in one car and the fourth in another.

“We don’t know for sure what (the victims’) social status is. Looking at the videos, they were asleep on the train,” Chin said.

A suspect was taken into custody about an hour an a half after the shooting, which investigators believe to be an isolated incident and a random attack, police said. Surveillance video was instrumental in identifying the suspect, police said.

“The CTA has great cameras. Their surveillance cameras are excellent,” Chin said.

Three agencies — Forest Park police, Chicago police and the CTA — worked together to track and capture the suspect, Chin said.

Chin told CNN the suspect likely exited the train at the Harlem stop on CTA’s Blue Line. He eventually got on the Pink Line, where he was apprehended by police. Law enforcement also recovered a firearm.

“I was able to watch some of the videos and it seems like they were able to track, locate and then identify or at least be able to pinpoint … OK, this is who Forest Park is looking for. And Chicago was able to nab him and we were able to swoop in and take him into custody.”

WLS
Forest Park Deputy Chief Chris Chin speaks at a Monday news conference.

“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 transit authority said in a statement.

As investigators continue to comb through the evidence, prosecutors will have 48 hours from the time of his arrest to announce any charges against the suspect.

“This obviously is shocking, you know, it is uncommon to have a mass shooting like this,” said Chin. “This is an isolated incident, so it can happen anywhere. Obviously, there’s a little bit more concern because it is on a mass transit system,” he added. “For people to feel unsafe, it’s justified.”

CTA’s Blue Line spans 27 miles between O’Hare International Airport to Forest Park, passing through or near dozens of neighborhoods and downtown Chicago.

Forest Park Mayor Rory Hoskins said during a news conference the police and fire departments respond to the same area of Forest Park “probably more than any other location in our jurisdiction,” appealing to state leadership for additional public safety resources and law enforcement personnel.

He said he has traveled to Springfield in the past to call for more resources to deal with mental health and opioid addiction.

The mayor described this shooting an “outlier,” saying the city hasn’t really experienced this kind of shooting before.

Monday’s shooting is among 381 mass shootings in the United States so far this year, according to the Gun Violence Archive, which, like CNN, defines a mass shooting as one with four or more victims, not including the shooter. There have been an average of 1.5 mass shootings per day in the US in 2024.

Hours after the shooting, another passenger was seriously injured in a stabbing on the Red Line, Chicago police said in a statement. The incident began as a verbal altercation between a 37-year-old victim and an unknown man, who at some point took out a “sharp object” and repeatedly stabbed the victim, police said.

“The victim fled from the train at the Wilson Red Line station, and relocated, on foot, to the 4700 block of N. Broadway. The victim was then transported to Illinois Masonic Hospital initially listed in critical condition,” police told CNN.

A suspect in the stabbing has yet to be found and detectives are investigating.

This story has been updated with additional information.