Funeral Held For FDNY Chief Killed On 9/11

Pallbearers carry the casket during the funeral for FDNY Battalion Chief Lawrence Stack who was killed in the World Trade Center terror attacks of September 11, 2001, outside Saints Philip and James Roman Catholic Church June 17, 2016 in St James, New York. (Photo by Andrew Theodorakis/Getty Images)

Funeral Held For Fire Chief Who Died On 9/11

The funeral caisson fire truck during the funeral for FDNY Battalion Chief Lawrence Stack who was killed in the World Trade Center terror attacks of September 11, 2001, outside Saints Philip and James Roman Catholic Church June 17, 2016 in St James, New York. (Photo by Andrew Theodorakis/Getty Images)

Funeral Held For Fire Chief Who Died On 9/11

New York City Mayor Bill de Blasio attends the funeral for FDNY Battalion Chief Lawrence Stack who was killed in the World Trade Center terror attacks of September 11, 2001, outside Saints Philip and James Roman Catholic Church June 17, 2016 in St James, New York. (Photo by Andrew Theodorakis/Getty Images)

Funeral Held For Fire Chief Who Died On 9/11

A firefighter and his child at the funeral for FDNY head of the department's safety battalion Chief Lawrence Stack who was killed in the terror attacks of Sept. 11, 2001. (Photo by Andrew Theodorakis/Getty Images)

Funeral Held For Fire Chief Who Died On 9/11

Firefighters Lt. Michael Stack (white hat) and Brian Stack (dark hat) ride on the back of the fire truck during the funeral of their father FDNY Battalion Chief Lawrence Stack who was killed in the World Trade Center terror attacks of September 11, 2001, outside Saints Philip and James Roman Catholic Church June 17, 2016 in St James, New York. (Photo by Andrew Theodorakis/Getty Images)

Funeral Held For Fire Chief Who Died On 9/11

Flags attached to bagpipes are seen during the funeral for FDNY Battalion Chief Lawrence Stack who was killed in the World Trade Center terror attacks of September 11, 2001, outside Saints Philip and James Roman Catholic Church June 17, 2016 in St James, New York. (Photo by Andrew Theodorakis/Getty Images)

Funeral Held For Fire Chief Who Died On 9/11

Pallbearers carry the casket during the funeral for FDNY Battalion Chief Lawrence Stack who was killed in the World Trade Center terror attacks of September 11, 2001, outside Saints Philip and James Roman Catholic Church June 17, 2016 in St James, New York. (Photo by Andrew Theodorakis/Getty Images)

Funeral Held For Fire Chief Who Died On 9/11

Firefighters Lt. Michael Stack (white hat) and Brian Stack (dark hat) escort the casket from the back of the fire truck during the funeral of their father Fire Department of New York Battalion Chief Lawrence Stack who was killed in the World Trade Center terror attacks of September 11, 2001, outside Saints Philip and James Roman Catholic Church June 17, 2016 in St James, New York. (Photo by Andrew Theodorakis/Getty Images)

Funeral Held For Fire Chief Who Died On 9/11

New York City Mayor Bill de Blasio attends the funeral for FDNY Battalion Chief Lawrence Stack who was killed in the World Trade Center terror attacks of September 11, 2001, outside Saints Philip and James Roman Catholic Church June 17, 2016 in St James, New York. (Photo by Andrew Theodorakis/Getty Images)

Funeral Held For Fire Chief Who Died On 9/11

Pallbearers carry the casket following the funeral for FDNY Battalion Chief Lawrence Stack who was killed in the World Trade Center terror attacks of September 11, 2001, outside Saints Philip and James Roman Catholic Church June 17, 2016 in St James, New York. (Photo by Andrew Theodorakis/Getty Images)

Funeral Held For Fire Chief Who Died On 9/11

A sign on a funeral caisson fire truck during the funeral for FDNY Battalion Chief Lawrence Stack who was killed in the World Trade Center terror attacks of September 11, 2001, outside Saints Philip and James Roman Catholic Church June 17, 2016 in St James, New York. (Photo by Andrew Theodorakis/Getty Images)

Funeral Held For Fire Chief Who Died On 9/11

Pallbearers carry the casket during the funeral for FDNY Battalion Chief Lawrence Stack who was killed in the World Trade Center terror attacks of September 11, 2001, outside Saints Philip and James Roman Catholic Church June 17, 2016 in St James, New York. (Photo by Andrew Theodorakis/Getty Images)

Funeral Held For Fire Chief Who Died On 9/11

Pallbearers carry the casket during the funeral for FDNY Battalion Chief Lawrence Stack who was killed in the World Trade Center terror attacks of September 11, 2001, outside Saints Philip and James Roman Catholic Church June 17, 2016 in St James, New York. (Photo by Andrew Theodorakis/Getty Images)

Funeral Held For Fire Chief Who Died On 9/11

Pallbearers carry the casket during the funeral for FDNY Battalion Chief Lawrence Stack who was killed in the World Trade Center terror attacks of September 11, 2001, outside Saints Philip and James Roman Catholic Church June 17, 2016 in St James, New York. (Photo by Andrew Theodorakis/Getty Images)

Funeral Held For Fire Chief Who Died On 9/11

A giant American flag is hung between two fire trucks during the funeral for Fire Department of New York Battalion Chief Lawrence Stack who was killed in the World Trade Center terror attacks of September 11, 2001, outside Saints Philip and James Roman Catholic Church June 17, 2016 in St James, New York. (Photo by Andrew Theodorakis/Getty Images)

Funeral Held For Fire Chief Who Died On 9/11

Theresa Stack attends the funeral for Fire Department of New York Battalion Chief Lawrence Stack who was killed in the World Trade Center terror attacks of September 11, 2001, outside Saints Philip and James Roman Catholic Church June 17, 2016 in St James, New York. (Photo by Andrew Theodorakis/Getty Images)

Funeral Held For Fire Chief Who Died On 9/11

Theresa Stack holds the helmet of her husband during the funeral for Fire Department of New York Battalion Chief Lawrence Stack who was killed in the World Trade Center terror attacks of September 11, 2001, outside Saints Philip and James Roman Catholic Church June 17, 2016 in St James, New York.(Photo by Andrew Theodorakis/Getty Images)

Funeral Held For Fire Chief Who Died On 9/11

Pallbearers carry the casket following the funeral for FDNY Battalion Chief Lawrence Stack who was killed in the World Trade Center terror attacks of September 11, 2001, outside Saints Philip and James Roman Catholic Church June 17, 2016 in St James, New York. (Photo by Andrew Theodorakis/Getty Images)

Funeral Held For Fire Chief Who Died On 9/11

New York City Mayor Bill de Blasio attends the funeral for FDNY Battalion Chief Lawrence Stack who was killed in the World Trade Center terror attacks of September 11, 2001, outside Saints Philip and James Roman Catholic Church June 17, 2016 in St James, New York. (Photo by Andrew Theodorakis/Getty Images)