Goodguy A is standing over BgA, gun trained on em.
Badguy B is standing nearby, gun trained on GgA.
Goodguy B is standing nearby, gun trained on BgB.
This is not a complicated standoff. GbB shoots BgB, blam. Point blank. In the head. The probability that BgB can react quickly enough to shoot GgA is pretty close to nil. BgA is then questioned. And, in this case, perforated with exceptional prejudice.
Oh, sorry, NO. I'm wrong, CLEARLY GgB needs to surrender her weapon to BgB, so both goodguys can be captured by the bad guys.
I'm sorry, but Gwen Cooper is a LOUSY COP. I don't care if they do things differently in Wales, she's a lousy LOUSY cop.