Funeral of 9/11 Fire Chief Lawrence Stack

The flag-draped casket of New York Fire Department Battalion Chief Lawrence Stack is carried out of his funeral in St. James, N.Y, on Friday, June 17, 2016. Walking behind the casket in white is his widow, Theresa Stack. Friday would have been the couple’s 49th wedding anniversary. Stack died at the World Trade Center in the Sept. 11, 2001 terrorists attacks.

Firefighters salute during the playing of “Amazing Grace” at the funeral for FDNY Battalion Chief Lawrence Stack on Friday, June 17, 2016, in St. James, N.Y. Stack died in the Sept. 11, 2001 terrorist attacks at the World Trade Center.

Long Beach Calif., Fire Chief Rich Brandt displays bracelets with the names Port Authority Police Officer George Gerard Howard and New York City Fire Department Battalion Chief, Lawrence T. Stack, both of whom died in the Sept. 11, 2001 attacks on the World Trade Center, during Stack’s funeral in St. James, N.Y., Friday, June 17, 2016. Stack’s remains were never found, but his family is burying two vials of his blood that they recently discovered. Brandt started his career with the FDNY and was friends with Chief Stack.

Brothers, New York Fire Department Lt. Michael Stack left, and firefighter Brian Stack, ride the back of a fire engine bearing the remains of their father, FDNY Chief Lawrence Stack, during Stack’s funeral in St. James, N.Y., Friday, June 17, 2016. New York City Fire Chief Lawrence Stack died in the Sept. 11, 2001 terrorist attacks at the World Trade Center.

New York City Mayor Bill de Blasio arrives at the funeral for Battalion Chief Lawrence Stack on Friday, June 17, 2016, in St. James, N.Y. Nearly 15 years after the Sept. 11 terror attacks, a funeral is being held for a New York City fire chief who died in the World Trade Center collapse. Stack’s remains were never found, but his family recently discovered two vials of blood that he had donated during a bone marrow drive for a child with cancer.

A fire truck displays a sign honoring FDNY Battalion Chief Lawrence Stack, who was killed in the World Trade Center terror attacks of September 11, 2001.