The death toll from monsoon floods in India, Bangladesh and Nepal has climbed above 1,200, as rescue workers scramble to provide aid to millions of people stranded by the worst such disaster in years.

All three countries suffer frequent flooding during the June-September monsoon season, but international aid agencies say things are worse this year with thousands of villages cut off and people deprived of food and clean water for days.

Indian Prime Minister Narendra Modi conducted an aerial survey of flood-hit Bihar state on Saturday and has pledged a relief fund of $78m.

A flash flood emergency has been declared in the Houston area of Texas by the National Weather Service after water reached the second floors of houses south of the city. The heavy rains were brought about by hurricane Harvey, now downgraded to a tropical storm.

Government officials in India’s eastern state of Bihar told Reuters news agency on Friday that at least 379 people had been killed over the past few days, with thousands sheltered in relief camps away from their inundated homes.

Some rivers in the Houston area were at around eight to ten feet (2.4-3 meters) over their banks, WBTV reported.

Over a thousand people have been rescued from the affected area since early Saturday.

“I know for a fact this is the worst flood Houston has ever experienced,” Patrick Blood, National Weather Service meteorologist, told the Houston Chronicle.

Blood warned that the “catastrophic flooding in the Houston metropolitan area is expected to worsen.”

The National Weather Service has warned that rainfall from Hurricane Harvey could reach 50 inches (1.27 meters) in some places, which would be the highest-ever level registered in Texas.

George Bush Intercontinental Airport in Houston has announced the cancellation of commercial flights due to the flooding