How to create an impacting suicide scene??(need any ideas)?

They are in a very tense situation in a diner and somehow the male ends up turning a gun against somebody and just cracks and shoots the person, they then realise what they've done and start shooting everyone, the SWAT team is alerted, she forgives him for what he did and when they have no ammo they run outside and both aim the gun at the cops so they shoot them down, they then find out that the gun was empty.