Eleven people have died of heatstroke in India after a million people waited hours in the sun for a government-sponsored award ceremony, officials said Monday.

About 20 people were taken to hospital and about 300 felt unwell during the event, which was held near the city of Bombay (west) on Sunday, when the temperature approached 38 degrees Celsius with high humidity levels, according to local media.

Senior government officials attended the ceremony, including Home Minister Amit Shah, who praised the crowd for waiting hours in the sun.

In turn, the minister responsible for the state of Maharashtra, Aknat Shinde, described what happened as a "sad and disturbing incident", pledging to provide compensation to the relatives of the victims.

And the ruling Indian Bharatiya Janata Party reported that about a million people attended the event, according to the "Indian Express" newspaper.

For its part, the opposition Congress Party accused the government of negligence and said it should face criminal charges.

Heatwaves have killed more than 6,500 people in India since 2010, while last year records were recorded in several cities across the country.

Scientists report that heatwaves are becoming more intense and frequent across South Asia, driven by climate change.

And the West Bengal state authorities announced the closure of all schools, colleges and universities for a week, starting from Monday, as a result of the heat, according to local media.

India suffered last year from a shortage of coal, the main source of electricity in the country of 1.4 billion people, while demand for electricity reached its peak in light of the heat.

Many parts of India depend on trains to provide water during the summer.

Scientists also believe that the annual rainy season is becoming more intense and more irregular, leading to more floods.