Apartment leasing problem (no legal knowledge...help!)

Hi everyone,

My roommate and I signed a lease for a new apartment with an exact move-in date (next month). With only 3 weeks left until the beginning of the lease, the Management called us to tell us that the former tenants decided to extend their lease and thus the room will no longer be available.

Can we take legal action on this?
We’ve already paid a $100 holding deposit for the apartment, signed the lease, and everything else (security deposit, first month’s rent) was supposed to be due @ the time when our lease began.
From my understanding, the holding deposit should ensure us the room and prevent anybody else from taking it.

Please let me know if I’m wrong on any of the stated points, and what action my roommate and I can take at this point.
Any help would be GREATLY appreciated!!