Well, the regular Police Constables here don’t carry guns - Only specialist teams carry guns, meaning that this was likely part of a planned operation. You’d only have armed units attempting to arrest someone if it was planned in advance.
Absolutely no information has been released by the Police so far, other than to say that a man died during a shooting incident and the force has referred itself to the ICPP (Public body that investigates allegations of misconduct against the police - Pretty sure all Police forces have to refer themselves if someone is shot by an officer as a routine thing).
Officers are only supposed to shoot to kill if, quote, “there was some imminent threat to life and that the officer must be able to justify, under the law, that their action was reasonable force to protect themselves or others.”
Since no information is available yet, nobody is in a position to say anything. We don’t know who the man was, if he was armed and dangerous, etc. I am sceptical by default, however, so we will have to see.