CHICAGO — A 21-year-old man was injured during an attempted robbery on a CTA train.

The incident happened around 11 p.m. Thursday at the Roosevelt “L” stop. According to a police investigation, an armed man attempted to rob the 21-year-old at gunpoint while riding the CTA train.

An altercation between the two men turned physical and the offender began to struggle over the gun, causing it to discharge, police said.

The 21-year-old was transported to Northwestern Memorial Hospital in fair condition, but police said he was not shot during the altercation.

The offender was arrested and charges are pending. Area Three Detectives are investigating.