Rubble piled up on the street below and cars were half-buried, but 10 families were safely evacuated from the building on Piazza Gentile da Fabbriano, near the riverside in northern Rome, and without any injury, Roma Today reported.
The fifth, sixth and seventh floor collapsed at around 4am in what one resident said “felt like an explosion”.
“We thought it was a bomb,” the resident told the newspaper.
Their lucky escape was down to an engineer who lives on the second floor. Alarmed by creaking sounds coming from the seventh floor, neighbours called on the expert for help.
She noticed cracks on the walls, and so alerted the fire service, who advised residents to leave the building.
Six teams of firefighters were dispatched to the scene.
The cause of the collapse is yet to be established but it was reported that it could be due to internal building works.
A stretch of road along Rome's riverside was closed to traffic on Friday morning, with police advising drivers to take alternative routes.