An EMP attack at this point requires a very large device or a nuclear detonation. Neither one of which were observed.
They were announcing the power outage because the first bomb or two took out the power lines that are run in the tunnels, and they hadn't gotten any reports of actual bomb detonations since radios and cell phones do not work in the subways there.
Makes sense.
Would think such a thing would have resulted in more widely reported disruption.