Transocean Deepwater Horizon Explosion-A Discussion of What Actually Happened?

A good article about the recent oil platform explosion in the U.S. with lots of technical details and eye-witness accounts. [Link]

Witnesses state that the lights flickered on the Deepwater Horizon. Then a massive thud shook the vessel, followed by another strong vibration. Transocean employee Jim Ingram, a seasoned
offshore worker, told the U.K. Times that he was preparing for bed after working a 12-hour shift. "On the second [thud]," said Mr. Ingram, "we knew something was wrong." Indeed, something was very wrong.
Within a moment, a gigantic blast of gas, oil and drilling mud roared up through three miles of down-hole pipe and subsea risers. The fluids burst through the rig floor and ripped up into the gigantic draw-works. Something sparked. The hydrocarbons ignited. In a fraction of a second, the drilling deck of the Deepwater Horizon exploded into a fireball. The scene was an utter conflagration.