Zorab
"If the engines had been shut down, Police radios will be un-powered anyway, with the possible exception of a hand-held radio, if fitted, in the cradle - although unlikely in the confusion that either Police occupant will have time, or presence of mind, to change the rotary selector (from where it's likely to have been for normal Ops) to be able to transmit."
This was a discussion point on ground vehicles (before mobile phones) with emergency services, do you loose comms, or wire radios before isolators, some county's did others didn't.
Would tend to agree with FFF not enough bandwith