Tsunami timeline question:

[wonder9]

I posted this question on another forum, which was dumb, because it really fits here. Anyway...
Help me out with the tsunami timeline. How long was it between:

A) The sea receding prior to the first wave

B) The first wave hitting

C) The subsequent waves hitting

I mean at any one place, not the actual first wave of the tsunami tragedy. I'm puzzled by the number of reports of people going out on the exposed ocean floor to pick stuff up. I don't understand how much time was passing.