Re: "Massey died in a fusillade of bullets"
" a fusillade is a simultaneous and continuous firing from multiple firearms at a target or group of targets"
Correct, it doesn't require multiple parties exchanging fire. Even the 'continuous' condition isn't necessary, one round of simultaneous fire also counts as a fusillade. I believe it evolved from a battlefield term restricted to rifles (fusil) being simultaneously fired, to being most commonly associated with a firing squad. In Italian, the term 'fucilata' can also be used for a single shot from a single rifle.