Military helicopters are leading rescue operations in India’s flood-hit northern states, where 130 people are now known to have died.
Some 18 helicopters have rescued 5,000 people in the worst-hit Uttarakhand state, an army official told the BBC.
Tens of thousands of pilgrims are stranded in Uttarakhand, where more than 100 people have been killed.
Flood-related deaths have also been reported in Himachal Pradesh and Uttar Pradesh states.
The monsoon season generally lasts from June to September, bringing rain which is critical to India’s farming output, but this year the rain in the north of the country has been heavier than usual.
A military statement quoted by the AFP news agency said five airbases had been activated to help speed up rescue operations.
“Indian Air Force helicopters carried out missions to airlift men, equipment, relief material and medical aid,” the statement said.
The situation in Uttarakhand was “really very bad”, top disaster management official Piyush Rautela was quoted as telling AFP.
The floods have swept away buildings and triggered landslides in some places, blocking roads. More than 20 bridges have collapsed.
Portions of a Hindu temple in Kedarnath were washed away and the shrine was “submerged in mud and slush”, Uttarakhand disaster relief minister Jaspal Arya said.
India’s Home Minister Sushil Kumar Shinde said more than 62,000 pilgrims were stranded at various places.
Most of the pilgrims – bound for local Himalayan shrines – are stranded in Rudraprayag, Chamoli and Uttarkashi districts after roads caved in and bridges collapsed.
Some of the pilgrims who are stranded in a guest house in Joshimath town spoke to the BBC Hindi’s Shalini Joshi about their ordeal.
“We were stuck in the car for 14 hours, we spent the entire night there. The mountains were collapsing above us, while a river in spate was raging below us,” Delhi resident Asha Mahajan said.
“There was a huge traffic jam, we could neither go forward, nor move back. Anything could have happened. It was raining heavily and we were afraid that there might be a landslide. Thank God we are all right,” she added.
“This is the first time we’ve come to the mountains. But we’re now stuck in Joshimath. We are so close to the holy shrine of Badrinath, but we’ve been told not to go there. It makes me really said, but what can we do? If I survive, I’ll come back here,” said Dineshbhai Kishanbhai Patel who is visiting from the western state of Gujarat.
“It’s been a harrowing trip for us,” said Trilochan Singh from Mumbai city. “We hear the roads are all broken, cars and shops have been swept away. It is frightening. We are very lucky to be alive.”
Local officials told the BBC that the number of dead was expected to rise as rescue workers had still not reached many affected areas.
In Himachal Pradesh, where at least 10 people have been killed in landslides, Chief Minister Virbhadra Singh was himself stranded in Kinnaur district for nearly 60 hours.
He was evacuated on Tuesday by a helicopter hired by his Congress party, reports said.
Indian Prime Minister Manmohan Singh has promised “all assistance in rescue and relief operations” in Uttarakhand, a statement issued by his office said.