CHICAGO — Police are investigating after a man was found dead in a stairwell at a CTA Blue Line station early Saturday morning.

According to the Chicago Police Department, a 54-year-old man was found unresponsive in a stairwell landing around 4:01 a.m. in the 100 block of West Congress Parkway.

The man was taken to Northwestern Memorial Hospital where he was pronounced dead.

Police have one person in custody and the incident has been classified as a death investigation, pending autopsy results.

“CTA is working closely with Chicago Police regarding an incident last night at the LaSalle Blue Line station involving a CTA employee,” the CTA said in a statement.

No other information is available at this time.