Timothy O'Brien, 40, Rockville Centre, N.Y. Cantor Fitzgerald Dead, World Trade Center, on the ground

Patrick O'Keefe, 44 Dead, World Trade Center, on the ground

Gerald O'Leary, 34 Dead, World Trade Center, on the ground

Maureen Olson, 50, Rockville Centre, N.Y. insurance broker, Marsh Inc. Dead, World Trade Center, on the ground

John P. O'Neill, 50 director of security, World Trade Center Dead, World Trade Center, on the ground

Sean O'Neill, 34, Rye, N.Y. Cantor Fitzgerald Dead, World Trade Center, on the ground

James Robert Ostrowski, 37, Garden City, N.Y. Dead, World Trade Center, on the ground

Timothy O'Sullivan, 68, Albrightsville, Pa. financial consultant, Cultural Institution of Retirement Systems Dead, World Trade Center, on the ground

Jason Oswald, 28, New York, N.Y. bond broker, Cantor Fitzgerald Dead, World Trade Center, on the ground

Peter J. Owens, Williston Park, N.Y. Dead, World Trade Center, on the ground