Neighbors feared a vacant decrepit Brooklyn building would collapse someday — and yesterday, it did, displacing adjacent families.

Residents angrily blamed the 3 a.m. collapse of the two-story home at 552 Ovington Ave. in Bay Ridge on Mousa Khalil, a real-estate speculator who bought the property in 2006.

But Khalil yesterday blamed delays fixing up the place on problems getting city building permits.