Urgent landleech question, advice needed

My roommates are surprise moving out and they said the landlord told them that they have to get their part of the deposit from me, ie "no fuck you if you want your part of the deposit you paid me, get it from ShimmeringKoi." When asked, he just said "California law" and also said we have 24 hours to decide if we're still on the lease or not.

I can see the 24 hour thing maybe being official, but the deposit thing immediately scans as bullshit, what can I do about it?