The tube was shut down almost immediately. It more or less shut itself down.
I don't know what you've heard, but the first explosion looked, to the controllers, as though two trains in the central part of the system had collided and sent a power surge across the network. This, in itself, enough to put most of the system out of commission.
Because the explosions happened underground, the only initial source of information was through sensing equipment. I think it was only when the bus was blown up in Woburn Place that it was realised what precisely was happening.