I agree with @thomasrutter, but if you're willing to do some up-front planning and some work after-the-fact, or try some other things there may be some other options. It will of course depend on the shot you're trying to get. These ideas probably aren't ideal for candids.
Photograph the room without the people in it, then have them come back and photograph it again with settings/lighting that makes the people look how you want. If you use a tripod and don't move the camera between shots, you can layer the two photos in your favorite editing app and paint the people into the room (so long as your careful to also get their shadows, reflections, etc.). You can even do a long exposure for the room and a shorter exposure for the people. You'll want to make the exposure of the people match the exposure of the empty room photo so it doesn't look weird, of course. But that can be handled fairly easily by the exposure control in your editing app. (You may also need to match the grain depending on how different the people end up from the clean room shot.)
Another option is to photograph the room, and photograph the people separately against a blue or green screen. You can then use compositing software to remove the blue/green screen and put the people into the room. As above you'll need to be careful with shadows/reflections and you'll need to match lighting, exposure, and possibly grain.
And don't be afraid to pose people. If you require a longer shutter to get the shot, have the people stand very still in the pose you like. It's not always appropriate, but it can work in a pinch.