Chicago Police Department Public Transportation tweeted Friday that an airsoft pistol was recovered from the person of interest's backpack.
The first attack occurred on Aug. 2, shortly before 7 a.m. on the CTA Blue Line-Clinton platform.
The second incident happened on Aug. 4 shortly before 9 a.m. at the CTA Blue Line-Western station.
In both attacks, police say a man approached the victims, a 21-year-old man and 39-year-old woman, and struck them in the head with a handgun that he pulled from his backpack.
"I mean it’s crazy, but then again, it’s Chicago, you always gotta be aware," said Jason Galon of Wicker Park.
The attacks come after several reported stabbings in previous weeks on the CTA.
In addition to other citywide violence, those who have no choice but to rely on public transit say they’re now paying extra attention to their surroundings.
Galon says when on the train, he’s now looking around more, with his headphones off and his iPhone in his pocket.