It would be similar to the shooting here of Andrew Kernan back in ‘01. He was in an aggressive and agitate stated and CS gas didn’t work.Yes - if they were all armed, a bloke armed with a sword attacking random members of the public, colleagues and who had the sword raised as they confronted him would clearly pose a lethal level of risk to them and anyone nearby.
As such they’d be justified in using lethal force to stop him.
He came at a prone officer with a raised samurai sword, so he was shot. It was regrettable that a man died, and more so an unwell one….
… but in the circumstances it was justifiable. Likewise, we have a dead boy here and two cops seriously injured, so he’d have been justifiably shot.