CHICAG0 (CBS) — For the second time in 48 hours, a Chicago police officer has died at the Calumet District station on the Far South Side.

Sources said a 47-year-old officer was found unconscious at her post around 4 a.m. at the female lockup at the Calumet District station at 727 E. 111th St., after possibly suffering a heart attack. She was taken to Advocate Trinity Hospital, where she was pronounced dead.

“A very hard day for the CPD as we grapple with the unexpected death of a #ChicagoPolice officer who fell unconscious at work this morning. This comes two days after another tragedy where an officer took his own life after battling personal hardships. Deepest condolences to all,” Police Department spokesman Anthony Guglielmi tweeted Tuesday morning.

The officer’s name has not been released, but sources said she is a 13-year veteran of the force. A procession of Chicago police vehicles escorted her body to the Cook County Medical Examiner’s office Tuesday morning.

Her death comes two days after another officer, 36-year-old Brandon Krueger, committed suicide in his vehicle in the Calumet District station parking lot. He was pronounced dead at the station at about 7:30 p.m. Sunday. An autopsy Monday determined he died of a self-inflicted gunshot wound.