9/11 ceremony live updates: Families to gather at WTC, Pentagon, Shanksville to mark 25 years

The sixth moment of silence was held at 10:28 a.m., to mark the moment the World Trade Center's North Tower collapsed, nearly 30 minutes after the South Tower fell.

The president addressed the crowd at the 9/11 ceremony at the Pentagon.

Trump reflected on the horrors of the attack and the thousands killed in on 9/11, but noted the strong response from America against its enemies.

"That's why we fight today," he said. "We do not have a choice, we can only have victory."

The fifth moment of silence was held at 10:03 a.m., to mark the moment passengers on United Airlines Flight 93 fought back against the hijackers, resulting in the plane crashing into a field near Shanksville, Pennsylvania.

The reading of the names at the 9/11 Memorial & Museum ceremony was paused once again at 9:59 a.m., when the fourth bell tolled, marking the time the World Trade Center's South Tower collapsed.