PURNIA, India (CNN) -- As soon as the navy boats hit the water, hundreds of villagers swarmed around them -- pleading with rescue crews to head to their homes to retrieve the bodies of dead relatives.
Children at a makeshift camp in the flood-hit Purnia district share a meal.
The crew explained that it could not. Its mission was to reach villagers stranded on rooftops and in trees, nearly two weeks after the worst flooding to hit the Indian state of Bihar.
The crowd drowned out their answers with angry shouts.
The Indian federal government estimates three million people have been affected by flooding in Bihar.
Authorities in Nepal said the waters had displaced more than 100,000 Nepalese. Watch as massive rescue effort continues »
Indian federal and state governments have released conflicting death tolls for Bihar. The latest figure released by the federal government put the number of casualties at 54.
Fifteen navy boats took off on a rescue operation in Purnia Monday, one of the districts hardest hit by the flood.
They were part of a massive relief operation underway in the northeast Indian state -- even as the misery that the Kosi River had wrought showed little signs of abating.
On August 18, a dam in Nepal broke, breaching the eastern embankment of the Kosi. The waterway straddles the India-Nepal border.
Water flushed through the breach so forcefully that the river changed course in Bihar. It gobbled up thousands of villages on either side of the border. Watch a doctor's efforts to help child survivors in Bihar »
Government and aid agencies swung into action to help the thousands of people who fled the fast-moving waters. Officials set up 182 camps where 114,000 residents have sought shelter, the interior ministry said Monday.
Food there is scarce, but the crowded camps sit on dry grounds.
But many are yet to be rescued. Officials worry that in coming days, stranded residents may take to drinking the contaminated river water -- raising fears of an epidemic.
The navy boats Monday carried life jackets and water. Crews scanned the horizon, looking for hope amid the hopelessness that stretched for miles.
The relentless monsoon rains that caused the Kosi to overflow in India and Nepal also brought anguish to neighboring Bangladesh. Floods there have marooned at least 20,000 people in the northern part of the country. Forecasters said the situation could worsen in the next few days because all major rivers were expected to rise by six inches a day.
Monsoon rains sweep across the subcontinent from June to September. While they bring much-needed relief to often-parched farmlands, they also leave a trail of landslides, home collapses and floods.
CNN's Sara Sidner contributed to this report.
All About India