At least two people were killed and 18 others injured as a severe dust storm hit Delhi on Sunday evening, while air traffic and Metro service too was disrupted due to strong winds and accompanying rain, officials said.

Power supply was affected in many areas in Delhi and Gurugram in Haryana.

In Sarita Vihar area in southeast Delhi, a tin sheet blown off a rooftop by strong wind hit pedestrian Rohit, 22, injuring him seriously. He was rushed to Apollo hospital where he was declared brought dead.

In Pandav Nagar area in east Delhi, Sonwati, 56, died after a tree fell on her, police added.

At least 18 persons were injured across the city.

As the storm blew at a high speed of 70 km per hour, mercury crashed from 39 degrees Celsius at 4 p.m. to 25 degrees half hour later in the national capital, the India Meteorological Department (IMD) told IANS. By early evening, the skies had turned dark.

More than 70 incoming flights were diverted from the Indira Gandhi International Airport (IGIA) here in the evening after the powerful dust storm and rain reduced visibility, an airport official said.

An IGIA official said the diversions took place between 4.15 p.m. and 9 p.m.

"Till 9 p.m. more than 70 flights have been diverted and a few outbound flights have been delayed due to the ongoing weather condition," the official told IANS.

Delhi Metro operations were also hit. Thousands of commuters were stuck on the winding and busy Blue Line, which links Dwarka in west Delhi to Noida and Vaishali in Uttar Pradesh, for more than 45 minutes.

The Violet Line, one of the six lines of the Delhi Metro that connects Kashmere Gate in north Delhi to Escorts Mujesar in Faridabad in Haryana, was also disrupted.

In both cases, trees toppled and damaged overhead Metro wires, an official spokesman said.

When the Metro services finally resumed after about two hours, the trains were run haltingly.

The rain and storm uprooted trees and broke tree branches in some Delhi areas and led to traffic snarls, forcing persons riding two-wheelers to take shelter under bridges, flyovers and other concrete structures. Motorists switched on headlights to find their way in growing darkness.

The Delhi Fire Service said it had received over 30 calls on falling trees and two calls related to wall collapse within two hours of the dust storm.

The dramatic change in weather, however, did bring respite to residents from sweltering heat.

The MeT department had forecast rain and thunderstorm with gusty winds on Sunday.

Mahesh Palawat, Director of the private weather forecast agency Skymet, told IANS that the change in weather was due to western disturbance which reached Jammu and Kashmir and Himachal Pradesh on Saturday evening.

"A cyclonic circulation formed near Haryana and north Rajasthan along with the western disturbance. South-easterly and easterly winds are creating moisture and high temperature in the region which caused the formation of thunder clouds. The strom blew over a trough which is spread from north Rajasthan and Uttar Pradesh.

"Delhi falls within the trough, but now this will move towards western Uttar Pradesh. There is a likelihood of light rains with thunder towards the afternoon or evening for two more days. Westerly winds will form again and temperature will begin to rise after May 15," Palawat said.

Just after the dust storm hit Delhi and the National Capital Region, Delhi, Gurugram and Noida received heavy to moderate rains.

The MeT official said Sunday morning was the hottest of the season, with minimum temperature recorded at 30.6 degrees Celsius, five notches above the season's average.