US marks anniversary of 9/11 attacks

>>> good evening on this tuesday, september 11th . a date that will always and forever mean just one thing on the calendar. especially for all of us who were alive that day. and most especially for those who lost someone on that day. every year on this day, we pause. bells toll and taps is played in many places. this year, especially coming off the tenth anniversary last year, a lot of people noticed a change. today's date remains cemented in history as the day that changed everything in the modern era . ron allen starts us off tonight from the world trade center site in lower manhattan . ron, good evening.

>> we're on the 22nd floor of the new world trade center . you can see the memorial down there, set in the footprints of the original twin towers . today's event was more intimate than many others. it generates powerful emotions.

>> and my uncle, whom my brother and i missed meeting by ten days.

>> reporter: the tradition of honoring each of the individuals lost lives on. with only their relatives reading the names.

>> dominick e.talia.

>> reporter: politicians were excluded for the first time, to keep the focus on the families. president obama led a moment of silence at 8:46 a.m ., the time the first plane struck the north tower . and later, laid a wreath during a tribute at the pentagon, where 184 people were killed.

>> this is never an easy day, but it is especially difficult for all of you.

>> reporter: in shanksville, pennsylvania, vice president biden comforted families. while in nevada, mitt romney struck a patriotic tone. during an appearance at the national guards meeting. this anniversary seemed more private than public. many communities like glenrock, new jersey which lost 11 residents chose not to hold a formal observance for the first time. this always will be a deeply personal day for those who lost loved ones. like rob fazio. who says the stories he heard about the heroism of someone trapped on the 99th floor.

>> he held the door open to help someone. we saw that as an inspiration of how he lived his life.

>> reporter: his foundation, hold the door open helps people deal with grief.

>> the south tower of the world trade center was gone.

>> reporter: new stories are still emerging, one in a new documentary airing tonight on discovery. pasquale says he's finally able to talk about how he survived, sliding from the 22nd floor to the top of a pile of rubble as the building collapsed around him.

>> i didn't feel anything. my body was totally numb. i felt nothing at all. i opened my eyes and saw blue sky . i really thought i was dead.

>> reporter: a group of firefighters rescued him. many said they wanted to honor first responders who gave their lives and saved so many lives that day. brian?

>> ron allen starting us off in lower manhattan tonight.