On 4 April 2013, a building collapsed on tribal land in Mumbra, a suburb of Thane in Maharashtra, India. It has been called the worst building collapse in the area. Seventy-four people (18 children, 33 men and 23 women) were killed, while more than 100 survived. The search for additional survivors ended on 6 April 2013.The building was under construction and did not have an occupancy certificate for its 100 to 150 low- to middle-income residents. Living in the building were the site construction workers and families. It was reported that the building was illegally constructed because standard practices were not followed for safe, lawful construction; land acquisition and resident occupancy.

By 11 April, a total of 15 suspects were arrested including builders, engineers, municipal officials and other responsible parties. Governmental records indicate that there were two orders to manage the number of illegal buildings in the area: a 2005 Maharashtra state order to use remote sensing and a 2010 Bombay High Court order. There were also complaints made to state and municipal officials.

On 9 April, a campaign began by the Thane Municipal Corporation to demolish area illegal buildings, focusing first on "dangerous" buildings. The forest department said that it will address encroachment of forest land in the Thane district. A call centre was established by the Thane Municipal Corporation to accept and track resolution of caller complaints about illegal buildings.