Resident Evil 4 Help me!

[Nosophoros]

Ok I got the wii version and I got up to the part where Ashley drives that huge truck thing up to a room where you have to hit a switch to open the door. I basically have no ammo! HOW DO I GET PAST IT!!! Can I hit the switch and run back down or do I have to kill everyone?inch:

 

[L]

You go up push the switch kill the ganados crowiding ashley and your out.

 

[Nosophoros]

OK...

But if I try that and jump back on the back of the truck won't the ones up the ladders come down?

 

[L]

No, once the screen goes black the ganados are gone.