A 57-year-old Rikers Island inmate died in an apparent suicide early Monday, authorities said.

Segundo Guallpa was found unresponsive in his cell in the North Infirmary Command and pronounced dead at 1:30 a.m. after first-responders were unable to revive him, said the city Department of Correction.

“This is a terrible tragedy. We have been in contact with Mr. Guallpa’s next of kin and extended our deep condolences,” said DOC Commissioner Vincent Schiraldi in a statement. “We are providing assistance to our fellow law enforcement and oversight agencies as we conduct a full investigation.”

Guallpa was detained at the city jail Aug. 19 on a charge of second-degree strangulation, the agency said.

The DOC said it has notified Guallpa’s lawyer.

The city Medical Examiner’s Office will determine the exact cause of death.