No casualties.
Wiki:The Lockheed test crew then assessed that the computer used to command the firing of the rockets during the landing sequence needed further calibration, and elected to manually input commands.
The reverse-mounted (forward-facing) eight ASROC rockets for decelerating the aircraft's forward speed were situated in pairs on the fuselage's upper curvature behind the cockpit, and at the midpoint of each side of the fuselage beneath the uppers.
Testing had determined that the upper pairs, fired sequentially, could be ignited while still airborne (specifically, at 20 feet), but that the lower pairs could only be fired after the aircraft was on the ground, with the descent-braking rockets also firing during the sequence.
The flight engineer, blinded by the firing of the upper deceleration rockets, thought the aircraft was on the runway and fired the lower set early. The descent-braking rockets did not fire at all…….
As a result, the aircraft's forward flight was immediately reduced to nearly zero, dropping it hard to the runway and breaking the starboard wing between the third and fourth engines.
During rollout, the trailing wing ignited a fire, but a medical evacuation helicopter dispersed the flame and crash response teams extinguished the fire within eight seconds of the aircraft stopping, enabling the crew to exit the aircraft safely…..