Why did US indiscriminately attack civilian targets in Kyushu in WWII's final stage?

CHIKUSHINO, Fukuoka -- Mysteries still shroud a tragedy 80 years ago in which many civilian passengers died in U.S. military attacks on running trains

Why did US indiscriminately attack civilian targets in Kyushu in WWII's final stage?
CHIKUSHINO, Fukuoka -- Mysteries still shroud a tragedy 80 years ago in which many civilian passengers died in U.S. military attacks on running trains