CHICAGO (WLS) -- Six people are in custody after a stabbing attack on board a CTA Red Line train on the North Side Friday morning, Chicago police said.
The violent armed robbery ended with at least four people stabbed, including three of the six attackers.
CTA riders are shocked by news of another stabbing on public transportation. This time, at the red line stop at North & Clybourn.
"What can you do? I mean it's terrifying a little bit yeah," said Olivia Chumbler, who rides the CTA. "I'm kind of weary of riding it now."
Chicago police said at about 2:03 a.m., a 42-year-old man got off a train at the North/Clybourn station and switched to another train car.
A group of six suspects followed him onto the train, demanded his belongings and attacked him with a knife and broken glass bottle, police said. The victim also took out a knife, police said.
WATCH: CPD give update on CTA Red Line stabbing
During the struggle, the victim took out a small knife from his pocket and stabbed one of the offenders, a 24-year-old man, in the back.
That's when a fourth suspect entered and began attacking the victim.
The man continued to defend himself, stabbing that second attacker, a 52-year-old man, in the neck.
"The victim was then chased around the platform and train cars by a total of six offenders," CPD Superintendent David Brown said Friday afternoon.
The terrorized victim was hit in the head with a glass bottle and had several stab wounds, police said. He was transported to Northwestern Memorial Hospital in serious condition.
"I get off work at 12 o'clock/midnight and the subway, it's critical down there. They're sleeping in the subway, smoking weed, gangbanging on the subway. And it's dangerous," added Darryl Berry, who also rides the CTA.
Police said six suspects are in custody and three of them were injured in the attack.
The 52-year-old man stabbed in the neck was transported to Stroger Hospital in serious condition, police said. The 24-year-old man stabbed in the back was transported to Northwestern Memorial Hospital, where his condition stabilized, police said. A 36-year-old man also sustained lacerations on his forearm and was transported to Stroger Hospital in fair condition.
Neighbors said they generally feel pretty safe aboard the CTA, but the most recent act of violence has them raising their eyebrows.
"It definitely affirms my belief that I should not take it at night," resident Kiley Nieneyer said. "It's unfortunate that that kind of thing happens. I've definitely had a lot of friends that have had some rough encounters."
Ben Paese said he rides the CTA three to four times per week and said he feels mostly safe, but avoids riding late.
"There are times when I try to keep my headphones in and keep my head down," Paese said.
After learning of the attack, he said his evening commute might change.
"I'm probably not going to take the 'L' home at night anymore or this weekend," he said.
"It's very concerning that this is our public transit system and this is what's happening," added anoter rider who didn't want to be identified. "Everyone riding every day. You see kids, you see college kids on the train, and it's just very concerning."
The CTA said in a statement, "This kind of violence is absolutely unacceptable, and we applaud the Chicago Police Department for its quick actions to arrest the suspects. CTA will continue to assist CPD in its investigation, including sharing any video from our security camera system."
Normal service has resumed at the North/Clybourn station.
Area Three detectives continue their investigation and charges are pending.