A man was stabbed on a CTA Red Line train along the Dan Ryan Expressway early Sunday morning.

At 2:51 a.m., the 34-year-old man was on the Chicago Transit Authority train when he got into a quarrel with another man as the train was at the 69th Street stop, police said.

Police said the attacker stabbed the first man in the chest.

The victim was taken to the University of Chicago Medical Center in serious condition, police said.

No one was in custody Sunday morning.

On Monday night last week, a man and woman were stabbed on the platform for the 69th Street Red Line stop.