umm. looking at the shadows, it seems like the light source is pointed directly at the subjects, from about standing head height. Doesn't seem toobright, but is shot with a flash, to create that 'flat' look. There isn't a fill light that I can see. Usually stuff like this might also be lit from above to fill (and reduce image flatness), but this isn't.
I don't know what do call that other than Direct lighting.
Its hard to say for sure how it was done with this small of an image. My best guess is a single light source just to the left of the photographer. Probably with a softbox or an umbrella reflector, but maybe not.
I think the lighting is too even for it to be a flash - there is no light gradiation at the top of the photo, and flashes are usually really directional. And it could go either way between single source and cluster.