"He ran into a building to rescue people, and then the worst that could happen, happened to him," PBA President Pat Lynch said.
Officer Guerra along and his partner Rosa Rodriguez, who remains in critical condition, were overcome by smoke and fumes as they answered a 911 call of a fire in the hallway of a city owned building in Coney Island.
During the service, their bravery was remembered by Mayor Bill de Blasio.
"We'll always remember with sorrow how Dennis left us that day, but we'll also remember with pride the example of valor and devotion to duty that he set," de Blasio said.
He also carried on a tradition as a NYPD officer following his father and uncle onto the force.
"He was a senior officer who was very respectful and responsible. He acted with dignity and he wore the uniform with honor and pride," Deputy Inspector Carlos Valdez said.
His brother-in-law Curtis Mitchell remembered his devotion to family.
"He was recently called a hero, but to all of his family Dennis was always a hero. And long before he will continue to live on in our hearts and memories as such," Mitchell said.
Honored one last time, as his coffin was carried from the church, a precision flyover, by the department's aviation unit.