How did sirius die in 911?

Sirius Black, a character from the Harry Potter series, did not die in the 9/11 attacks. He died in 1996 during a battle with his cousin, Bellatrix Lestrange, in the Department of Mysteries in Harry Potter and the Order of the Phoenix.

It's important to remember that Harry Potter is a fictional world, and the real-life events of 9/11 are unrelated to the book series.