Within one second of detonation, the fireball generated in the air grew to a diameter of 280 meters. It blazed for approximately 10 seconds. For three seconds beginning 1/100 of a second after deto-nation, heat rays emitted in all directions by this fireball ex-erted powerful effects at ground level. Temperatures in the hypocenter vicinity reached 3,000-4,000 degrees. People sustained severe burns from the powerful heat rays and thousands died as a direct result. The burns were only on the side directly facing the epicenter, but as far as 3.5 kilometers away people suffered burns on exposed skin. The surface of root tiles within 600 meters of the hypo-center melted and blistered. Out to 1.8-2 kilometers, cloth- ing on bodies or drying on the line ignited. Approximately 2.5 kilometers away, thatched roofs went up in flames. Mary trees spontaneously ignited. Within 3 kilometers, electric poles, trees, and lumber were charred.