At least 10 districts of Assam were reeling under flood water with the Asia's largest river island Majuli and the Kaziranga National Park being the worst affected, officials said.
Rising water of the Brahmaputra has inundated vast tracts of land in Kaziranga's Burapahar, Bagori and northern parts of Agratoli.
The situation in the world's largest island was also grim with the water level of the Brahmaputra flowing above the danger level at Majuli, Kamalabari, Nematighat and Jhanjimukh affecting over 45 villages with an estimated population of 25,000.
Vast areas of agricultural land have been inundated with severe scarcity of drinking water reported from most of the villages.
A 10-member team from the State Disaster Response Force (SDRF) was camping at Majuli island to conduct rescue operations in the villages submerged during the third wave of flood this year.
Nearly four lakh people have been affected in 28 revenue circles and 615 villages in the 10 districts - Bongaigaon, Chirang, Dhemaji, Jorhat, Golaghat, Lakhimpur, Morigaon, Nagaon, Nalbari and Sonitpur.
At least 77 relief camps have been set up in the affected districts with the district administration providing relief, the officials said.