State officials said the army is using boats to rescue marooned people in northern and western parts of the state.
The flooding is the worst in the past three years, affecting nearly 600,000 people in 19 of the state's 27 districts.
Police officer Diganta Borah said a van carrying wedding guests plunged into a river Friday night in Dhubri district. Rescuers found four bodies Saturday and rescued six occupants, the Associated Press reported on Sunday.
Other deaths from drowning were reported in Korajhar, Nalbari and Barapeta districts.
The area is prone to flooding during the June-to-September monsoon season.