NEW YORK (CNN) -- Mourners gathered in New York Saturday at funerals for three top officials of the city's fire department killed in the aftermath of Tuesday's attacks on the World Trade Center.

Fire Department Chief Peter Ganci; First Deputy Fire Commissioner William Feehan; and Father Mychal Judge, the department's chaplain, were laid to rest Saturday in services attended by hundreds of firefighters and police officers from New York and surrounding communities.

"Today was a very solemn and difficult day in New York City, with the three funerals we had for Bill Feehan, for Pete Ganci and for Father Judge," Mayor Rudolph Giuliani said at a news conference Saturday evening. "Unfortunately, it is an indication of what we are probably going to face in the future."

"They are heroes," Giuliani added. "They are like the heroes we had at Pearl Harbor. Each one of them were trying to save lives."

Ganci, a 33-year veteran of the department, died fighting the fires in the famed twin towers after two hijacked airliners plowed into the structures. His white chief's helmet lay on his casket during the service in Farmingdale, on Long Island.

Ganci, 54, survived the first tower's collapse and ordered the fire command post north. Ganci then ran south to make sure everyone was evacuated and was killed when the second tower came down.

The Rev. John Delendick, who was also on the scene at the time of the building's collapse, reminded the packed crowd in St. Killian's church that Ganci died performing the service that he loved.

About 300 firefighters are still unaccounted for in the wake of the disastrous attack.

Fallen chaplain 'loved his fire department'
Judge, 68, was killed by falling debris while administering last rites to a dying firefighter. At the Church of St. Francis of Asissi in midtown Manhattan, Father Michael Duffy recalled Judge as someone who loved to be where the action was.

"He loved his fire department and all the men in it," Duffy said. "And that's the way it was when he died on Tuesday." Sen. Hillary Clinton, D-New York, recalled that she and former President Bill Clinton invited Judge to a White House prayer breakfast after hearing about the "charismatic Franciscan."

"He lit up the White House as he lit up every place where he saw himself," she said. "Father, you gave us so many gifts when you were alive: gifts of laughter and love."

The funeral for Feehan, 71, took place Saturday morning at a church in the city's northeastern borough of Queens. He had spent nearly 40 years with the department.

Fire Commissioner Thomas Von Essen has announced that 166 firefighters will receive promotions in a ceremony Sunday, with their command effective immediately. Many of the promotions are necessary to replace firefighters killed in the collapse of the World Trade Center towers.