More than 100 people have died due to flooding after three days of heavy rain in the populous Indian states of Uttar Pradesh and Bihar.

National disaster management chief SN Pradhan said thousands of people were being evacuated from the Bihar state capital, Patna, calling the situation “unprecedented”.

The city is among the worst-affected regions, after exceptionally heavy rainfall from the retreating monsoon. In total, 29 people have died in Bihar and at least 79 have died in Uttar Pradesh since Friday.

Officials in Bihar say it is the worst incident of its kind in decades. The state government has requested two Air Force helicopters be deployed for airdropping supplies and lifting the wounded out of flood-affected regions.

Schools have been ordered closed until at least Tuesday as a preventive measure. The forecast is for the rains to abate significantly in the coming hours.

Of 19 national relief units deployed to Bihar, five are in Patna, Mr Pradhan said. Authorities in the city have deployed boats to rescue residents stranded in their homes.

They included the state’s deputy chief minister, senior BJP politician Sushil Modi, who was shown in social media videos with his trousers rolled up, being rescued by boat from his flood-stricken residence.

Yet while many have been moved to dry land and given tents by the government, others complained of a lack of state aid. Bihar consistently lags behind as India’s poorest state, both in terms of incomes and public infrastructure.

Ananju Devi told the Associated Press the supplies were not reaching people like him. “We are unable to cook any food. How can we? We are just sitting around and getting by somehow,” he said.

The flooding has been particularly bad in villages, towns and cities which, like Patna, sit on the already swollen River Ganges.

Such towns include Ballia in Uttar Pradesh, where on Monday officials said almost 900 prisoners were being moved out of the district jail after flood-waters entered the cells.

Though the floods are worst in Uttar Pradesh and Bihar, many states also experienced heavy rainfall over the weekend. In Gujarat, three women drowned after their car was swept away at a flooded causeway, the Press Trust of India reported, while 13 deaths in total were reported across Uttarakhand, Madhya Pradesh and Rajasthan states.