I learned it was Father Mychal Judge, a chaplain with the FDNY, who died being hit by debris in the lobby of WTC Tower 1.
The following summary is from a review of a documentary about his life, written by Stephen Holden in the NY Times.
By the time of his death, at 68, Father Judge had been sober for 23 years and had saved countless lives by taking people to Alcoholics Anonymous. One man remembers living in a box on the street until Father Judge found and rescued him.The movie is called The Saint of 9/11. It's available on NetFlix.
His sexual orientation, which he acknowledged to friends but kept largely hidden from his colleagues at the Fire Department, led him to work closely with the gay Catholic organization Dignity and brought him into conflict with the conservative Catholic establishment. He marched in a St. Patrick’s Day parade organized by the gay activist Brendan Fay, a prominent talking head in the film and one of its producers.
In the early days of the AIDS epidemic, when even medical personnel were fearful of physical contact with quarantined patients, Father Judge ministered to dying young men at St. Vincent’s Hospital and physically embraced them. Even when he encountered hostility from patients who wanted nothing to do with religion, he discovered that rubbing their feet with holy oil before talking with them would usually break down their resistance.
In the film’s most resonant speech he offers comfort to the families of those who died in the crash of TWA Flight 800 off Long Island in 1996. Repeated by Mr. McKellen near the end of the film, they serve as a benediction:
“God is present, loving, smiling, having received our loved ones. They are in his presence, illumined by his smile, and warmed by his love. His kingdom is enriched this day, so enriched by so many beautiful souls, so much beauty.”