As many as 4,157 villages across 30 districts of the northeastern state, including Dhemaji, Lakhimpur, Biswanath, Sonitpur, Darrang, Udalguri, Baksa, Barpeta, Nalbari, Chirang, Bongaigaon and Kokrajhar, were submerged as the rain continued unabated.
The number of dead also increased to 15, with four people losing their lives on Monday.
Nearly 43 lakh people across 30 of the state's 33 districts have been affected by the floods so far. Barpeta was the worst-hit district, with as many as 7.35 lakh people facing the brunt of the monsoon fury, followed by Goalpara, Morigaon, Nagaon and Hailakandi.
The rising water level of the Brahmaputra river is threatening to submerge parts of the state capital, Guwahati, through which it flows. The ten other rivers in the state also swelled up dangerously as the rains continued.
As many as 83,000 people evacuated from flooded areas have been accommodated in 183 relief camps across the state. Road connectivity to Upper Assam has been cut off. Ferry services were called off earlier due to water strong currents.
Forest officials said that 95 per cent of the Kaziranga National Park -- home to the endangered one-horned rhino -- has been flooded with the death of 17 wild animals in the past two days. Animals could be seen emerging out of the park to escape drowning.
Agricultural activities in the state have also been hit, with nearly 90,000 hectares of agricultural land getting flooded. Many such fields had standing crops on them
According to the state government, 15 National Disaster Response Force (NDRF) teams comprising 380 personnel have been deployed to rescue people from flood-affected areas. The state health department has also been instructed to address medical issues arising from the situation.
Flood control mechanisms, including control rooms, have been pressed into service with state government officials manning them round the clock, Chief Minister Sarbananda Sonowal said. The veterinary and animal husbandry department has also been directed to help marooned animals, he added.
State ministers and public representatives have also been asked to help victims of the floods and personally supervise rescue operations, the Chief Minister said.
Prime Minister Narendra Modi had called up Mr Sonowal on Monday to take stock of the situation. The Chief Minister apprised him of the largescale destruction caused by the floods, and provided details of the relief measures being undertaken.
The Union government has assured the state of all possible support and cooperation in this regard. Home Minister Amit Shah had earlier directed central agencies, including the NDRF, to leave no stone unturned to help in rescue and rehabilitation efforts.