Floods caused by incessant rains in the country over the past week have displaced hundreds of thousands of people in the east and northeast, destroyed crops and damaged bridges, officials said on Friday.
In Bihar, 21 people have died while hundreds of thousands of villagers have seen their houses washed away while road and rail networks have been disrupted by heavy monsoon rains over the past three days.
"The floods have damaged 1,776 houses in 269 villages across the north of Bihar and we are sending relief to the marooned villagers," said Manoj Kumar Srivastava, a Bihar disaster management official.
Parts of Patna are also waterlogged, resulting in many people remaining at home and some private schools being shut.
In the northeast, rivers -- including the mighty Brahmaputra -- have burst their banks and floodwaters have submerged around 10,000 hectares of paddy fields and destroyed hundreds of houses.
"The situation is grim," said Bharat Chandra Narah, flood control minister for Assam.
In the mountainous state of Arunachal Pradesh, roads were blocked by landslides, while fast-flowing rivers eroded river banks and damaged bridges.
Weather officials predicted more rains in the next 48 hours across Bihar and the northeastern states.
(Additional reporting by Biswajyoti Das in Guwahati)