Chalk artists have gathered at the Flight 93 National Memorial in Shanksville, Pennsylvania, to draw portraits of the 40 passengers and crew members killed on September 11, 2001.
The group of 20 artists is creating the portraits ahead of the 25th anniversary of the attacks, with each drawing offering a personal tribute to those who died aboard United Flight 93.
Among the works is a portrait of one of the passengers remembered for taking part in the attempt to regain control of the hijacked plane. Another artist is drawing the youngest person aboard the flight, saying the work has a strong personal meaning.
The chalk portraits are temporary and will gradually fade while on display at the memorial.