The National September 11 Memorial Museum to open to public in May

Those most affected by the Sept. 11, 2001, terrorist attacks will have five days to visit the memorial museum in New York before it opens to the public.

The committee behind the National September 11 Memorial Museum announced Monday that the public opening is May 21. For the five days before that, the museum will be open 24 hours a day for relatives of those killed in the attacks, emergency responders whose departments lost members and residents and business owners in the neighborhood.

Almost 3,000 people died in the attacks, 2,753 when two hijacked planes flew into the twin towers of the World Trade Center, causing both to collapse. The rest were killed when another hijacked plane hit the Pentagon and a fourth crashed in Shanksville, Pa., after passengers attempted to retake it.

Tickets will be available on the museum's website starting March 26. Victims' family members and registered first responders will be admitted without charge.

The museum stands on the site of One World Trade Center.

[9/11 Memorial]