Residents in many parts of Bangalore spent a sleepless night because of heavy rain that lashed the city overnight, evoking memories of the flooding just over a month ago.

The latest spell of rain attributed to low pressure in the Bay of Bengal had left the city and many parts of the state wet. But a day of sunshine on Wednesday had encouraged people to step out in the evening. However, the skies opened up around 9pm and led to a massive downpour that went on unabated almost through the night.

While residents in upscale gated communities in areas like Yamalur near the old airport stayed up watching the water levels, which, however, didn’t swell like last time, slums that accommodate migrant labourers in east Bangalore were left flooded with knee-deep water by Thursday morning.

The India Meteorological Department on Thursday put Bangalore on yellow alert and forecast more rain till October 23. The city received 60.5mm rain on Wednesday.

Bruhat Bengaluru Mahanagara Palike chief commissioner Tushar Giri Nath on Thursday said his department was on the job to ease the flooding. “The east zone was very badly affected by rain (on Wednesday) and we are doing everything to help the people,” he said, adding that more workers had been deployed to pump out water and clear clogged storm water drains.

Social worker R. Kaleemullah told The Telegraph that his group organised some water pumps to clear floodwater in Munnekolala, a short distance from the tech neighbourhood of Marathahalli. “The major storm water drain in that area had been flowing almost to the brim when rain lashed the area last night. This caused overflowing and flooded the shanties,” he said.

A resident at a gated community in Yamalur, who did not want to be identified, said he was among those who stayed awake until early on Thursday to ensure water levels did not rise like last month. Residents of several gated communities in the area had to be evacuated in tractors, leaving their expensive cars behind, during the flooding in early September.

“I have already lost two cars that had to be written off due to flooding last time. But luckily water levels did not rise this time,” he said.

What seemed to have helped is the reopening of a major storm water drain that was encroached by the gated communities in the area.

But residents in many other parts of the city were not so lucky as hundreds of vehicles got stranded late on Wednesday. Several underpasses were among flooded spots where vehicles sputtered to a stop.

Taxi driver John Ebhen said all roads from the Kempegowda International Airport were waterlogged due to the overnight rain. “It was a nightmare as many drivers, including me, had a tough time ferrying travellers to and from the airport. Many roads were inundated until about 4am.”

A retaining wall along the Bangalore Metro line collapsed in Sheshadripuram, damaging several cars and two-wheelers.

Waterlogging was witnessed in upscale residential neighbourhoods such as Indiranagar and Koramangala. But these areas dried up by morning, although a few waterlogged spots caused traffic snarls.