[aristeides]

Spiegel article confirms there are witness reports of several explosions in the building: "Augenzeugen berichteten, in den oberen Stockwerken sei es zu mehreren Explosionen gekommen. "

[codebreaker]

Footage of choppers landing and rescure personnel taking victims out of the building on CNN.

[r9etb]

Spiegel article confirms there are witness reports of several explosions in the building:

Not implausible: start off with a lot of fuel igniting in an enclosed space. If there's more than one tanks (e.g., a center tank and one in each wing), then other tanks could explode separately.