"Sorry, mum. Got a job to do, people to save. The building thinks the Inferi are a contagion; so the only way to get out is to kill the disease, or the building. Good news, though: a lot of them seem to be bound to their beds as if St Mungo's is trying to restrain the illness from spreading. However, the magical matrix is pretty damaged here, the building wasn't designed to withstand this much magic being thrown around recklessly. If you gave to, kill the building to escape."