By Jeremy Ross

CHICAGO (CBS) —The attack so horrible, the victim may never see again. And police just announced they are questioning someone.

CBS 2’s Jeremy Ross reports from the CTA Red Line’s Jarvis stop.

The incident took place around noon Thursday. Chicago police said a suspect is in custody.

The train was heading north. It’s believed a woman was heading home.

She ended up taking a detour to the hospital.

A man caught on surveillance, his fist raised and the victim seated and reading her Kindle.

Police describe the attack as brutal, vicious and unprovoked.

The fear is the 67-year-old Evanston woman could lose her eyesight as a result of the blow to her head.

The attacker described as a man in his 20s, about 5’8″, 170 pounds, who at the time of the crime was wearing a short sleeve blue Illinois tee shirt.

All this taking place on a northbound Red Line train.

Police say the man eventually exited at Jarvis Avenue.

The CTA said in 2016 they recorded about one serious crime like this for every 250,000 customer trips.

Alderman Joe Moore calls the crime reprehensible but isn’t calling the violence an epidemic.

“As horrible as this incident is, it really is more of an isolated incident. Crime has gone down on the CTA considerably,” said Moore. “So I don’t think anyone should be afraid to ride the CTA. Having said that they should be alert.”

Moore added that it means taking our focus away from cell phones and being more aware of your surroundings while on the train or bus.

In a tweet, investigators say officers recognized a man from those surveillance images and took him into custody.