PHILADELPHIA (CBS) — The Philadelphia Fire Department is mourning one of its own after a firefighter died while on duty.

Fire officials say Firefighter Gabriel Lee of Ladder Company 12 died Saturday while working his night shift.

Lee was found unconscious at Engine 50 in the 1300 block of Cambria Street in North Philadelphia and then rushed to Temple Hospital.

Officials say Lee responded to a fire earlier Saturday morning and then returned to the firehouse to work the night shift.

Firefighters from another station were on hand to salute Lee as his body was escorted from the hospital to the medical examiner’s office.

Fire Commissioner Adam Thiel says firefighters are trying to rally together as they approach a difficult week ahead.

“We’re circling up and working together, the way we do as brothers and sisters, and doing right by Gabe,” he said.

Lee was with the department for more than 20 years. Funeral arrangements are pending.

The cause of his death is under investigation.