This is like Trumps outburst over that security guard who didn't go into the school all guns blazing when Trump said he would have done. Turns out the guard was following procedure and waiting for backup so as not to steam in and add to the gunfire and bloodshed.
So many people on here seem to have expert knowledge ( or think they have ) about what could and should have been done. Simple facts are these are one off events. There cannot be a dry run a perfect training exercise at the exact spot where something later happens so everybody knows where to be where to go like choreography. Think Bradford, think Kings Cross or Grenfell and even the Manchester bombing by the IRA. In all such cases emergency services follow a predetermined plan which has to be a one size fits all approach and so there will always be gaps, errors and the unforeseen. All that can be done is hope everybody did their best in the circumstances and that any lessons that can be are learned and taken forward. God forbid but when the next one happens there will be post event hand wringing and questions and some mistakes will inevitably be made then too - its what happens but its important to learn every time.