A woman and five children were killed in a building collapse in Mumbai on Sunday night as incessant monsoon rains paralysed India's financial capital, with at least 13 people dead across the region over the past four days and a red alert issued for continued heavy rainfall.A three-storey chawl, a row tenement common in Mumbai's older neighbourhoods, collapsed in the Mankhurd area, killing five young children and one woman, local authorities said. Search and rescue operations continued through the night as officials and residents feared more people were trapped under the debris.Some areas of Mumbai received more than 300mm of rain in a single day on Sunday, roughly half of what London would be expected to receive in an entire year. It was a record for rainfall across the city and nearby areas like Palghar and Raigad, according to Maharashtra's disaster management minister Girish Mahajan. Areas including Malabar Hill, Colaba, Vikhroli and Bhandup recorded over 200mm. The India Meteorological Department issued a red alert for extremely heavy rain and gusts of up to 90km per hour across Mumbai and neighbouring districts on Monday.Schools and colleges in Mumbai as well as the neighbouring cities of Pune, Thane, and Palghar were closed for the day. Private offices were advised to implement work-from-home arrangements and a half-day was declared for non-essential government offices. Flight operations at the Mumbai international airport were disrupted and the Maharashtra Legislative Council was adjourned.The death toll of 13 includes two people killed by falling trees. An 11-year-old boy was killed on 30 June when an uprooted tree fell onto a moving school bus and a 63-year-old man died on Sunday after a tree fell on him in the Navpada area of Kurla.The rain also caused roads to flood, with pictures circulating of commuters wading through chest-deep water and auto-rickshaw drivers pushing their vehicles through submerged streets.Police officers stand near a tree that fell onto a street during monsoon rains in Mumbai (AP)Mumbai, a megacity of roughly 20 million people, experiences severe flooding almost every monsoon season. Much of the city was built on reclaimed land and its drainage infrastructure struggled to keep pace with decades of rapid urbanisation. The 2005 monsoon remains the worst on record, when over 900mm rain fell over a single day, killing more than 1,000 people across the state of Maharashtra.Climate crisis is intensifying India's monsoon rainfall, with research showing that extreme rainfall events are becoming more frequent and more intense across the subcontinent. India relies on the monsoon for around 70 per cent of its annual rainfall, which sustains agriculture for hundreds of millions, but the rains increasingly arrive in concentrated, destructive bursts rather than steady seasonal showers.