This is the main point.
//Although two fire crews were stationed close enough to the Arena to hear the explosion, they were sent to a rendezvous point three miles away amid fears that there was a marauding terror attack and they would not be safe, the review concluded.
When they eventually arrived at the Arena, more than two hours after Salman Abedi detonated his suicide bomb on Monday 22 May 2017, the visibly frustrated fire officers were not immediately allowed on to the concourse to help because of communication errors between “risk-averse” officers in charge.//