Can you shoot the rest of a squads weapons at passengers if the vehicle is destroyed?

Something came up in a game I had today:-

Squad of marines shot down my raider with grots inside, the plasma gun was the first weapon he fired and that blew up the raider. My friend then wanted to shoot his remaining bolters in the same squad at the grots that emerged from the destroyed transport.
I didn't think you could do this.....he said as he could charge them it is logical that he could do this. We rolled a dice as we always do when we don't agree (it went in my favour) then looked it up after but could not find anything saying anything either way.
Essentially the unit inside is a different unit but as you can charge them after shooting the transport it does make sense you could fire the rest of your weapons at them.

Anyone else came across this?

For shooting, it'd be all at the transport.

No, you can't.
You have to shoot the same unit, so if you destroy the transport, the remaing weapons can't shoot the unit that gets out of it. In essence, all of a units shooting happens at the same time, so they all shoot the vehicle.
You are allowed to charge a unit that got out of a transport if you destroyed the vehicle though in shooting though.

This rule is the reason i like blasterborn in venoms.

troops in back can shoot a transport - destroy it.
the venom then can unlesh the duel splinter cannons into the unit as they disembark from the wreckage.

however if you do not explode the vehicle MOST players will put to transported units BEHIND the wreckage out of LOS.

That's why I love skimmers, the height advantage makes that much harder.

Yeah though, what your opponent tried to pull isn't legitimate. Not even with Power of the Machine Spirit.