A 46-year-old resident of Dharavi area of Mumbai who had contracted coronavirus died on Wednesday evening, prompting the civic authorities to seal the building where he lived.
Densely-populated Dharavi is famous as one of the largest slums in Asia.
The man, who lived in a building constructed under the Slum Rehabilitation Authority scheme, had no foreign travel history, said a health official of the Brihanmumbai Municipal Corporation.
After he died at nearby government-run Sion Hospital, some 300 tenements in the building and around 30 shops were cordoned off by police.
Residents of the building have been quarantined at home.
The deceased had a garment shop at AKG Nagar inDharavi, the official said.
Mumbai has recorded over 180 coronavirus cases and about a dozen deaths of COVID-19 patients so far.