Police in New York state say the man who lured firefighters to their deaths in a blaze of gunfire left a note saying he wanted to burn down the neighbourhood and "do what I like doing best, killing people."
Webster Police Chief Gerald Pickering said the man's sister had not yet been found.
He said 62-year-old ex-convict William Spengler armed himself with three weapons and set his house on fire to lure first responders into a death trap.
Two firefighters were shot dead and two others are treated in hospital.
Spengler killed himself as seven houses burned around him yesterday.