Twenty-five years later, John Ryan can still name all 37 Port Authority Police officers who died on September 11.

Christopher Amoroso. Antonio Rodrigues. J.D. Levi. Stephen Huczko. He ticks off their names and their special attributes.

Sgt. Robert Kaulfers stands out because he was one of Ryan’s closest friends on the job, the proverbial life of the party who would make up song lyrics on the spot and used his talents to make fun of colleagues. Ryan will always remember the laughs, but he remains haunted by the last time he heard his friend’s voice.

“You hear him calling on the radio, ‘West Street’s coming down, West Street’s coming down,’ and then nothing,” said Ryan, a former Chief of Department with the Port Authority Police Department. “You know by his description that he was in the lobby, in the South Tower, looking out, and could see the steel and other things dropping, and then ultimately, was killed in the collapse.”

Port Authority police lost more officers in the line of duty that one day than any other law enforcement agency has in a single day in US history.