What caused the massive fire in East Delhi's Vivek Vihar that killed 9

A massive fire erupted in a residential building in east Delhi's Vivek Vihar, resulting in the deaths of at least nine people, including a 1.5-year-old toddler. The fire reportedly started due to sparks in an AC unit, which quickly spread to at least six flats. Firefighters received a call about the fire at 3:47am and deployed 14 fire tenders, rescuing nearly 20 people. The Delhi government has expressed condolences to the kin of the deceased.