Relatives and friends of the more than 3,000 people killed in the Sept. 11, 2001 al-Qaida terrorist attacks are gathering in New York, Pennsylvania, Virginia and Washington, D.C. on Friday to mark the 14th anniversary, reports Reuters.

On Friday, people around the world remember the U.S. 9/11 terrorist attacks in 2001, which took the lives of 2,977 people, including 67 British citizens, when al-Qaida terrorists hijacked passenger jets and crashed them into the World Trade Center twin towers in New York City and the Pentagon in Arlington, Virginia.

Hijackers also crashed United Airlines Flight 93 into a field in Shanksville, Pennsylvania, when passengers onboard tried to regain control of the aircraft from the terrorists.

The New York ceremony will have moments of silence to mark the time the first plane collided with the north tower at 8:46 a.m., followed by the second aircraft striking the south tower at 9:03 a.m., as well as the times when the other two commercial jets struck the Pentagon and Pennsylvania field.

In New York, the names of those killed at the World Trade Center twin towers will be recited.

"We are not going to deviate from how it was done in the past. We'll start at 8:46 a.m. and the reading of names by family members won't likely be done for a few hours," Michael Frazier, a spokesman for the 9/11 Memorial in New York, told Reuters.

In Washington, D.C., President Barack Obama will lead a moment of silence to mark the 9/11 anniversary at the White House.

Defense Secretary Ash Carter will host a private ceremony for the relatives of those killed during the Pentagon attack.

Relatives and friends of the 40 passengers and crew members who died onboard United Airlines Flight 93 will gather at the dedicated Flight 93 National Memorial in Shanksville.

In New York, new residential and business towers has revitalized the area known after the terrorist attacks as ground zero. The One World Trade Center, the tallest skyscraper in the Western hemisphere, stands next to the 16-acre site where the twin towers once stood.

On Thursday, a rainbow appeared over the One World Trade Center in lower Manhattan around 8 a.m. -- one day before the 9/11 anniversary. Residents took pictures of the phenomenon, such as the one below, which have been widely shared on social media.