Both the left and right switchs were moved to ‘cutoff’, one pilot recognized this and asked the other pilot why, the other pilot denied doing it, then the switches were returned to ‘run’ and the engines began to re-light (this is all straight from the black box recorder). It was too late to recover though, so the plane went down.

There is a mechanical detent requiring you to pull each switch out, then down. They had to be moved deliberately.