The National September 11 Memorial dedication is scheduled for Sunday morning. With President Barack Obama arriving in New York, along with former president George W. Bush, Lower Manhattan is going through what resembles a lockdown.
On Saturday night, New York City police closed down all streets around the World Trade Center site and stepped up vehicle inspections on the perimeter. Military units were also deployed.
There is still no resolution to the two days old investigation of whether al-Qaida deployed three operatives to the United States to stage 9/11 car bombings in New York, Washington or other major U.S. cities. Federal intelligence analysts believe they have identified two of the three alleged terrorists but do not believe they are in the U.S.
"You use all the resources that we have, people are working 24/7 on this issue," said Rep. Dutch Ruppersberger, D-Penn.
Unanswered questions about the alleged terror plot hung over Saturday morning's 9/11 Memorial Parade.
"Don't let the terrorists take this day from us. What they do, they seek to impose fear and that's what this is about," said New York Gov. Andrew Cuomo.
But the threat didn't seem to turn any firefighters away from Saturday afternoon's Catholic memorial mass at St. Patrick's Cathedral, including more than 200 from Chicago and the suburbs.
"I think as a nation we were certainly rock solid ten years ago. I think people forget. But I think that's what anniversaries are for," said Chicago Fire Department Capt. Patrick Maloney.
"It's a bit of a pilgrimage for me. It's something, when I left here 10 years ago after coming out and trying to help, and thankfully I've been able to make it," said Steve Serb, engineer with the Chicago Fire Department.
When asked how many people he knew that died on 9/11, Western Springs Fire Department Officer Jim Regan replied: "I knew 17 firefighters and officers and 5 of them were very close friends of mine."
At the mass were families of many of the 343 New York City firefighters who died on 9/11.
"I know you're in heaven and always watching over me. I love knowing you are a hero. I wish I could have met you. Love, your son, Patrick Lyons," Patrick Lyons said.
