Under a gray and drizzly sky, thousands gathered around the sprawling, reconstruction site of the World Trade Center in New York City to take part in ceremonies, view memorials and commemorate the deaths of those killed in terrorist attacks six years ago on September 11.

Two hijacked planes crashed into twin office towers at the site and soon collapsed, while two other groups also hijacked and crashed planes into the Pentagon and at a field in Pennsylvania, claiming a total of nearly 3,000 lives.

A ceremony marking the time of the first office tower crash began with a moment of silence for the victims at 8:46 AM. The event took place at a small park just southeast of the WTC site as family members, friends, gathered, with many holding up pictures of loved ones.

Firefighters, police officers and other first responders read the names of all 2,749 victims killed, their voices often cracking with anguish as they recalled lives of those they worked closely with, many regarded as companions and close friends. Somber music played in the background. Also present were city and state officials, including Mayor Michael Bloomberg and Governor Elliot Spitzer.

Due to ongoing construction, the commemoration ceremony was held outside of the WTC site. However many of those gathered this year were allowed to descend along a long ramp into a simple memorial in the pit below. Many dropped off flowers and photos.

Various areas surrounding the site were restricted to family members, officials and the media. However some existing displays near the site were open to the general public and were adorned with flowers, flags, and memorials to the victims.

Prominent among the visitors were dozens of police, firefighters and emergency personnel in uniform from various countries who lined up along the east side of the site on Church Street.

One memorial along a display wall next to the site held a wreath wrapped with photos of six New York City firefighters killed during the attacks who had been dubbed the Monroe Six after the name of the street where their firehouse is located.