More than 500 people are now known to have died in monsoon rains in the Indian city of Mumbai (Bombay) and elsewhere in the state of Maharashtra.
In the latest incident, at least 15 people including several children were killed in a stampede in a Mumbai suburb following rumours of a dam burst.
Officials say they are struggling to restore calm among the population.
According to officials, the rain on Tuesday was the heaviest recorded in a single day in India.
More than 65cm (26 inches) fell in Mumbai.
"People died due to false rumours," R R Patil, the deputy chief minister of Maharashtra state told AP.
He said police vans with loudspeakers had been sent out to prevent similar incidents from taking place.
Half of the victims so far died in Mumbai where transport is still disrupted and trading on financial markets suspended. The navy is helping rescue efforts.
Thousands remain stranded amid fears the number of dead could rise.
Mumbai resident Sonali Mahajan e-mailed the BBC to say: "I waited at the office Tuesday night and then waded through chest deep water on Wednesday to get home, only to realise there's no electricity.
"I survived last night thanks to local residents out on the road in waist high water, who were handing out food and water to countless people walking home."
In a telegram issued from the Vatican, Pope Benedict XVI said he was praying for those killed and injured.
Those killed in the city were crushed by falling walls, trapped in cars or electrocuted.
The navy was called in to help 150,000 people stranded in offices, roads, airports and railway stations in Mumbai since Tuesday afternoon.
Many had to spend nights in offices as floodwaters raged through the streets.
Some flights are now operating from the international airport, which monsoon rains had flooded.
The Bombay Stock Exchange remained closed on Thursday with the state government urging citizens not to go to work.
The BBC's Zubair Ahmed in Mumbai says that most of the city's main roads are littered with vehicles.
Inter-city and commuter trains have been cancelled.
Outside Mumbai, two of the worst-hit areas are Raigad and Ratnagiri districts.
Communications outside the city are severely disrupted and there are conflicting reports about the number of deaths.
Food packets and water bottles are being air-dropped in the areas still flooded.
However there are fears waterborne diseases could bring a new crisis.
Reuters news agency says relief work is under way in the village of Juigaon, 150 km (90 miles) south of Mumbai, where up to 100 were thought killed in a landslide.
AP says 45 people were missing presumed dead in a landslide that hit shanty huts in the northern Mumbai suburb of Saki Naka.
One resident, Shabana Shaikh, said: "People ran as soon as the hill started crumbling. But the old people had no chance."
RV Sharma, director of the meteorological department in Mumbai, said most parts of India did not receive this kind of rainfall in a year.
"This is the highest-ever recorded in India's history," Mr Sharma said.
Officials said conditions were particularly bad because the rain had coincided with high tides.
The relief work in Maharashtra has been hampered by continuous rain.
More is forecast, although it is expected to be lighter.
Financial losses to Maharashtra have been estimated at more than $110m.
Monsoon floods at the end of June and early July left more than 50 people dead in neighbouring Gujarat state.