The floods swept away cars and caused buildings to collapse in Pune city [File: AFP]

At least 21 people have been killed and nine others are missing after the western Indian city of Pune and neighbouring areas were hit by heavy rain and flash floods, according to officials.

Authorities in Pune said on Thursday that 14 people were killed in the city following torrential rain the previous day. That included six people who died when a wall collapsed on them.

Five others were killed in the city when floodwaters swept across the Pune-Bengaluru Highway and washed away cars. 

In the neighbouring Jalgaon city, six others were killed as they took shelter from a thunderstorm under a tree, an official from the Maharashtra Disaster Control Authority told the Indo-Asian News Service.

Another person was killed in the city of Nashik. 

More than 28,000 people across the state of Maharashtra, where Pune is located, were evacuated from their homes and have been housed in temporary camps.

Local officials said about 150 homes have been damaged, leaving hundreds of families homeless.

Between Wednesday night and Thursday afternoon, Pune received more than 280mm of rainfall. Officials said it was the highest rainfall recorded in the region in the past 10 years. More rain was expected on Friday.

Pune District Collector Naval Kishore Ram declared a holiday for all schools and colleges in Pune city and neighbouring areas of Purandar, Baramati, Bhor and Haveli for Friday.

Ram added that Pune has received a record 180 percent of its annual seasonal total rainfall and all the dams in the district are overflowing for the first time in 22 years.

South Asia gets monsoon rain annually during the June-September months which cause fatalities and mass displacement.

During the monsoon season, which gets more than 70 percent of India's annual rainfall, are crucial for farm output and economic growth, but rainfall often weakens the foundations of poorly built walls and buildings resulting in deaths.