“A short circuit in the replaced main sequencer caused the second-stage engine to fire while being tested before launch. This detonated the first stage fuel tanks directly below, destroying the missile in an enormous explosion. Before seeking refuge, the camera operator remotely activated automatic cameras set around the launching pad that filmed the explosion in detail. People near the rocket were instantly incinerated; those farther away were burned to death or poisoned by the toxic fuel component vapors. Andrei Sakharov described many details: as soon as the engine fired, most of the personnel there ran to the perimeter, but were trapped inside the security fence and then engulfed in the fireball of burning fuel. The explosion incinerated or asphyxiated Nedelin, a top aide, the USSR’s top missile-guidance designer, and over 70 other officers and engineers. Others died later of burns or poisoning.[3][2][4][1] Missile designer Mikhail Yangel and the test range commanding officer survived only because they had left to smoke a cigarette behind a bunker a few hundred metres away, but nonetheless suffered burn injuries.[3][5]”