CHICAGO (CBS) — Someone hit a man with a hammer early Monday morning on board a CTA Red Line train in the River North neighborhood.

Police said, shortly before 2 a.m., officers responded to the Grand/State station on the Red Line, after a male passenger on a southbound train hit a 58-year-old man in the chest with a hammer.

The victim refused medical treatment at the scene.

The suspect was taken into custody.