A somber funeral service was held on Long Island Friday for a firefighter killed on Sept. 11.

FDNY Battalion Chief Lawrence Stack was given a hero's sendoff at Saints Philip and James Church. Though Stack's remains were never found, he had made a blood donation before the World Trade Center attack. FDNY Commissioner Daniel Nigro says the blood sample was recovered, which was enough for a funeral and burial.

Stack's two firefighter sons rode on the back of the firetruck carrying their father's casket. Lt. Michael Stack spoke during the funeral, telling mourners that his father saved lives right up until the very end.

"My father once told me heroes are ordinary people who find themselves in extraordinary situations - 9/11, 2001 was an extraordinary situation that was off the charts and Larry Stack was no ordinary guy," he said.

Firefighters lined the church steps as the casket was brought out of the church. The long procession headed to Calverton National Cemetery, the final resting place for the 33-year member of the FDNY and Navy veteran.

"We've moved forward, we've made the department real, real strong. We're in great shape. But we don't forget 15 years, 20 years. We do not forget," said FDNY Chief James Leonard.