[5] While still a volunteer with the Farmingdale Fire Department, Ganci was with the same friend one day who told him he was planning to transfer to another station in the city.

Following the conversation and his discharge from the Army in 1968, Ganci signed up and was accepted into the New York City Fire Department in 1968.

In January 1997 Ganci replaced his boss Donald Burns as Chief of Operations, the second highest uniformed position in the Fire Department.

[11] However, immediately after American Airlines Flight 11 hit the North Tower (1 World Trade Center) at 8:46 a.m. Ganci, Mosiello, and Chief of Operations Danny Nigro rushed there from their command post in downtown Brooklyn.

However, Ganci himself did not evacuate the area, saying, "I'm not leaving my men", and remained at that location with First Deputy Commissioner William Feehan.

[22] On September 8, 2020, it was announced that the James Gordon Bennett Medal for conspicuous bravery would be renamed for Ganci.