A man was stabbed on a CTA train platform early Thursday in the Loop.
About 2:45 a.m., he was with a group of people on a train platform in the 100 block of North State Street, when he began to argue with a male from the group, Chicago police said.
The male pulled out a knife and stabbed him in the chest, police said.
The person stabbed was taken to Northwestern Memorial Hospital in fair condition, police said.
The male who allegedly stabbed him was taken into custody but later released without charges, police said.
Investigators determined the man who was stabbed was the aggressor in the incident, and the male stabbed him in self defense, according to a police source.
Police believe the incident was drug-related.
Area Three detectives are investigating.