"Approximately 200 dead bodies have already been recovered in the state," R.R. Patil, deputy chief minister of Maharashtra state, told The Associated Press.
He said 100 more deaths were feared across the state, which has pounded swathes of India with incessant rainfall, since Tuesday afternoon.
Thousands of people have been stranded by rising waters in the financial capital Mumbai (Bombay), and emergency services and rescue teams were in operation on Wednesday.
"We have deployed the army to help people stranded and to evacuate those living in the low-lying areas," a government spokesman said.
"We have already evacuated around 10,000 people"
Indian government spokesman
"We have already evacuated around 10,000 people."
The army, navy and air force were called in to help as floodwaters swept the coast of Maharashtra state, with officials increasingly concerned about 150 people feared buried after a landslide in a village 150km south of Mumbai.
"We have not been able to reach some villages where more than several dozen people may be missing in landslides," state relief secretary Krishna Vatsa said.
Vatsa said the situation in the worst-affected region south of Mumbai was improving as the rains had stopped and water levels were receding.
But the rescue work was hampered because the weather had disrupted communications networks.
In Mumbai, meteorologists said heavy rains and high winds were forecast to continue for another 48 hours, after a record 94cm of rainfall in the north of the city during the previous day, the highest since 1974.
Mumbai's commercial district was
paralysed by rainfall
Electricity and phone links were cut in the city, schools were shut and commuters were stranded for a second day as trains and buses were cancelled.
Trading on the city's bond and currency markets was abandoned, flights in and out of the city were rerouted or cancelled and the government called a state holiday, advising people to stay home.
Flooding in the monsoon season in India, which runs from June to September, kills hundreds of people each year and disrupts life in wide swathes of land.