The death toll from this week's sudden heavy rain has climbed to 11 in New Delhi, including four citizens who drowned in submerged underpasses, the Times of India reported, while flight operations stuttered in the Indian capital.

New Delhi, which endured one of its worst heatwaves in history earlier this month, faced the biggest downpour in decades on June 28, with rainfall in a single day surpassing the city's average for the entire month.

The torrential rain caused a fatal roof collapse at one of the three terminals of Delhi's main airport, disrupted flights, flooded underpasses, and led to massive traffic jams, power and water outages in parts of the city.

Nearly 60 flights were cancelled from New Delhi's main airport in the last 24 hours, according to data from flight tracking platform Flightaware.

Operations were largely normal on Sunday, with most flights from the affected terminal diverted to the other two, an airport official said but did not rule out possible flight cancellations in the course of the day.

The Delhi airport is one of the country's biggest and busiest.

Terminal 1, the now-closed terminal, is mostly used by low-cost carriers IndiGo, operated by Interglobe Aviation , and SpiceJet, and currently has a capacity to handle 40 million passengers annually.

An Indigo spokesperson did not comment on the flight cancellations and a SpiceJet spokesperson did not immediately respond to a phone call.

(Reporting by Shivangi Acharya in New Delhi; Editing by Sonali Paul)