PATNA, India — Torrential rains pushed up water levels in rivers along the Himalayan foothills of south Asia on Thursday, where monsoon floods have killed more than 900 people and displaced or trapped more than 25 million.

Four more people drowned in eastern India on Wednesday and an overflowing river threatened to inundate low-lying areas around the populous capital city of Bihar state, relief officials said Thursday.

At least 904 people have died in monsoon floods across India, Bangladesh and Nepal.

The state's water department said heavy rains were pushing up the water level of Punpun River, which originates in Nepal and flows into Bihar, and could trigger fresh floods around the city of Patna by Friday. Patna is home to some 1.7 million people.

The water level in the Punpun River was 42 inches above the danger mark and might swell by another 34 inches over the next 24 hours, the department said in its latest update. Weather forecasts for the region called for continued rain through Thursday.

In Khagariya district, about 100 miles northwest of Patna, a postman was swept away, a 7-year boy drowned and two men died as their boat sank in the Gandak River, said the state's top relief official, Sambhu Saran Singh.

Flood waters also swept into the town of Khagariya, forcing authorities to shift dozens of prisoners from a local jail.

Rising rivers also submerged railroad tracks near Samastipur, 100 miles northeast of Patna, halting rail traffic for a large swathe of Bihar. Army soldiers in motorized boats were helping to evacuate thousands of villagers whose mud and thatch huts were washed away by raging flood waters.

The floods have destroyed about 2.5 million acres of maize in the state and affected more than 15 million people, Singh said.

The deaths in Khagariya on Wednesday pushed up the death toll in Bihar to 269, he said. Another 39 people have died in the northeastern state of Assam, and earlier this month, six people died when rains loosened a boulder that crashed onto shanties in Bombay.

In Arunachal Pradesh state, bordering China, seven soldiers were swept away while carrying out rescue operations a week ago, officials said.

New flooding in India's northeast swept two people away Tuesday in a remote village in Manipur state, bordering Myanmar.

About 7 million people have been hit by floods in the northeast and several key road and communication links have largely been cut off.

In all, monsoon floods have killed 323 people in India according to official estimates, though in most parts of the country rains have been delayed, damaging crops and causing the worst drought in 14 years.

Another 157 people have died in neighboring Bangladesh since the onset of monsoon rains in June. Water levels of the Ganges, Brahmaputra and Jamuna rivers, which had receded last week, began rising again Wednesday following fresh downpours in the country's northern region, Bangladesh's food forecasting center said. Monsoon floods have displaced more than 6 million others in the delta nation.

The highest death toll has been from Nepal, where at least 424 people have either been swept away by swirling floodwaters or crushed under mudslides in remote mountainous villages. About 250,000 people have been hit by torrential rains in the Himalayan kingdom, officials said.

Meanwhile, the International Federation of Red Cross and Red Crescent Societies has asked international donors for $1.7 million in immediate aid for the victims in Nepal and $1.9 million for those in India as emergency relief supplies have been exhausted.