I read a brief quote from a munitions expert today.
He said the plume of red colored smoke at the top of the mushroom cloud looks exactly like the red smoke from a certain kind of rocket propellant when a rocket blows up on the launch pad.
Since Hezbollah has like 150,000 missiles aimed at Israel, this is certainly a theory worth looking into.
I think I saw this quote and the photograph of the Beirut explosion on Gateway Pundit (not 100% sure about the name).