It seemed fitting, on Sept. 11, that D.C. Mayor Vincent Gray was interrupted by a blaring ambulance that raced past Freedom Plaza, where he was speaking on the importance of first responders, volunteers and community service.

"I hope that we will always remember the first responders who so courageously stepped up in New York, who courageously stepped up here at the Pentagon, who courageously stepped up and came to the rescue of so many people," Gray said Tuesday before stopping to appreciate the ambulance, which was coming by "right on cue."

America lost nearly 3,000 people in a series of four terrorist attacks that occurred on Sept. 11, 2001. Terrorists hijacked four planes, crashing them into the North Tower and South Tower of the World Trade Center in New York City and the Pentagon in Arlington. A fourth plane was headed to Washington, believed to be aiming for the White House or U.S. Capitol, when passengers revolted. United 93 crashed in a field near Shanksville, Pa.

Gray was speaking as a part of Serve DC and HandsOn Greater DC Cares's event to commemorate the September 11th National Day of Service and Remembrance as well as National Preparedness Month. Groups including the American Red Cross and Volunteer Fairfax had booths set up to educate the public on CPR, emergency preparedness and volunteer opportunities.

(View a photo gallery with more images from the Freedom Plaza event)

Judith Howell of the Fairfax County Community Emergency Response Team was there to teach people how to be resources for their families, neighbors and communities in the event of an emergency. As an Air Force veteran whose son was just deployed to Afghanistan, Howell said this event was particularly special.

"Being a military family, we know how important it is to serve our country," Howell said. "As a member of a CERT team, I'm helping people learn to serve others."

The event drew people from all areas of D.C., nearby workers on their lunch breaks, and tourists and visitors like Gloria Mayo Moreno, of Austin, Texas.

"Being here where the seat of our national government is and to feel the patriotism of the people and our loyalty to our country is pretty special," Moreno said.

Elsewhere in the city, the place known for hosting large, national events commemorating Sept. 11 simply added a few special prayers to its regular prayer services. The Washington National Cathedral hosted just about a dozen people at its 8:45 a.m. prayer service in its small Bethlehem Chapel.

Cleveland Park resident Brendon Fleming, who moved to Washington from New York City, said being able to commemorate the day in the National Cathedral was very meaningful to him.

"It's just important to me to take a moment to pause and reflect and remember, and I think it's important for the country to do that as well," Fleming said. "That's why I'm here."

While the memories of that day 11 years ago still linger in the minds of many Washingtonians, the city is ready to turn that dark memory around to make a positive impact, acting Secretary of Commerce Rebecca M. Blank said at the Freedom Plaza event.

"We can't change history. What we can change is the future, and that's what today is about," Blank said. "We are a nation that cares about our neighbors, wherever they are, and this day of service is a reaffirmation of that caring."