Texas holdem. If blinds r 400, small stack has 500 on the big blind, & they move all in, can u then re raise?

In texas holdem, if the blinds are 400 and the small stack only has 500 chips, and hes on the big blind (leaving him only 100 chips). If there are a couple of callers and then the big blind throws his other 100 in. Can one of the callers now re-raise? This came up at poker tonight. One guy said you could not, and he didnt look like he was bluffing :-D