April 26, 1:23:36 - 1:23:44 am

Thirty-six seconds after the test had begun, the shift supervisor attempts to drop all control rods back into the reactor realizing the power was rising beyond its limits.

In four and a half seconds, the power level inside the reactor rises 120 times the reactor's capacity.

The first explosion broke the pressure tubes, releasing steam which blew the containment lid off the reactor.