Shekalim, Chapter Six, Mishnah Two
This mishnah continues to discuss the hidden location of the Ark of the Covenant.
It once happened that a priest who was busy [there] noticed that the floor [of the wood storage area] was different from the others.
He went and told it to his friend but before he had time to finish his words his soul departed.
Then they knew for certain that there the Ark was hidden.
In this legendary tale a priest is busy chopping wood in the wood storage area of the Temple when he notices that the floor looks a little different. He rushes off to tell his friend about what he saw but before he can get the words out of his mouth, he dies (I hope his face didnt start to melt off. Indy should have told him to just close his eyes!). From this the other priests knew for certain that the Ark was hidden there.