Today is the anniversary observance of the most deadly terror attack on U.S. soil, when two hijacked planes were flown into the Twin Towers and caused their collapse. Two other planes were hijacked — one flown into the Pentagon near Washington D.C. and another crashed into a Pennsylvania field. Family members will again recite the names of 2,983 people, including those who died at the three sites, and in the World Trade Center bombing in 1993.