The incident took place late night when seven members of a family were sleeping on the second floor of their house and the roof collapsed on them, a police official said.
Sitaram (21), Ramasrey (19) Piyush (12) and Naimish (8) were killed and three others were seriously injured and referred to trauma centre Lucknow.
Another person sustained minor injuries.
The bodies have been sent for postmortem.
The slab was weak and the continued rains caused further damage to it, the official said.