[rec] 2 (2009)

aka REC 2: Fear Revisited.
"Through the sign of the cross, free us of our enemies, our lord."
Following on from Rec, the building has been quarantined, and a swat team are sent in to help a doctor ascertain what is going on. But when one of their number is attacked and the doctor subdues him with prayer, they know that there is more going on than they have been told.
Adding an element of demoniac possession to the story just takes away the impact of the first installment.