Construction crews started boarding up 552 Academy Street in Inwood on Saturday.
On Friday, the city issued a vacate order after inspectors deemed the building structurally unsound.
Residents had just hours to pack up and get out.
They say they considered the building a ticking time bomb since the roof caved in 5 years ago.
"This building is the poster child for landlord neglect," State Senator Adriano Espaillat said.
The Red Cross has been helping find displaced residents new places to stay.
The Buildings Department says it's conducting tests and doesn't yet know when residents might be allowed to move back in.