NEW YORK — Solemn crowds around the country gathered in silence Saturday for the 20th time to remember the nearly 3,000 people killed in the Sept. 11, 2001, attacks that forever changed the nation.

Bells tolled to signify the moments each tower of the World Trade Center was hit 20 years ago. Family members clutched photos of loved ones and wiped tears from one another’s eyes. In New York City, twin beams of light reached 4 miles into the sky in a haunting reminder of where the towers once stood.

Ceremonies were held Saturday in New York City, at the Pentagon and outside Shanksville, Pennsylvania, to honor the dead.

As survivors, politicians, first responders and loved ones of those who died reflected on the anniversary, many praised the unity Americans showed and highlighted the importance of passing on the memory of the day to those too young to remember it.

Former President George W. Bush recalled the unity and strength Americans showed 20 years ago, urging the country to put aside political views to come together again today. 

“So much of our politics has become a naked appeal to anger, fear and resentment,” Bush said at a private ceremony for family of those killed when United Airlines Flight 93 crashed into a field outside Shanksville, Pennsylvania. 

“On America’s day of trial and grief, I saw millions of people instinctively grab their neighbor’s hand and rally to the cause of one another.”

Bush, who was in office at