Officers observed 37-year-old Benjamin Kelly in medical distress at the Eric M Taylor Center on Rikers Island before 3 p.m. and provided medical assistance.
He was pronounced dead 31 minutes later.
In the second incident, James Malanado suffered a medical emergency around 4:30 p.m. while on a bus heading to Rikers Island.
He had not been admitted yet and was coming into custody for the first time after being discharged from a hospital before a court appearance.
Medical assistance was provided in the sallyport of the Eric M. Taylor Center.
He passed away at 4:49 p.m., according to officials.
The cause of their deaths is under investigation.
The NYC Department of Corrections issued a statement saying, "The life of every single person in our care is valued and Friday was profoundly tragic for the department as two individuals lost their lives."
Five inmates have died inside Rikers since the start of the year.
No other details were released.
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