Americans are marking the anniversary of one of the nation's most scarring days known as 9/11 today. Thousands of 9/11 victims' relatives, survivors, rescuers and others are expected to gather at the World Trade Center to remember the deadliest terror attack on American soil. <br/><br/>President Donald Trump, a native New Yorker observing the anniversary for the first time as the nation's leader, is scheduled to observe a moment of silence at about the time the first plane struck one of the Twin Towers on the morning of September 11, 2001. He also planned to participate in a 9/11 observance at the Pentagon. <br/><br/>Nearly 3,000 people died when hijacked planes slammed into the trade center, the Pentagon and a field near Shanksville, Pennsylvania, on September 11, 2001, hurling America into a new consciousness of the threat of global terrorism.