Did any kids died on September 11?

If you are referring to the September 11, 2001 terrorist attacks, yes. Eight kids died that day. This is the official list:

Bernard Curtis Brown II, 11 years old; passenger on Flight 77

Asia S. Cottom, 11 years old; passenger on Flight 77

Rodney Dickens, 11 years old; passenger on Flight 77

Dana Falkenberg, 3 years old; passenger on Flight 77

Zoe Falkenberg, 8 years old; passenger on Flight 77

David Gamboa-Brandhorst, 3 years old; passenger on Flight 175

Christine Lee Hanson, 2 years old; passenger on Flight 175

Juliana Valentine McCourt, 4 years old; passenger on Flight 175

Note: Flight 77 was the plane that hit the Pentagon, Flight 175 was the second plane that hit the World Trade Center in the south tower.