More than 50 people were killed in lightning strikes across several states in India, authorities said Monday, including 11 people at a historic fort.

Hundreds of people are killed each year in intense storms at the start of the monsoon season, which bring respite from the summer heat across the northern Indian plains.

Media reports said about 10 other people were killed Sunday in the desert state of Rajasthan and authorities added at least 42 died in different districts of Uttar Pradesh, India's most populous state.

In Jaipur, the capital of Rajasthan, bolts hit two watchtowers at the 12th-century Amer Fort, which were packed with visitors watching the storm cross the city.

"It was already raining when the people were there. They huddled in the towers as the rainfall intensified," Saurabh Tiwari, a senior Jaipur police officer, told AFP.

People had flocked to the fort, which gives a panoramic view across Jaipur, after several weeks of intense heat in the state.

Eleven people were killed and another 17 were injured, with three in critical condition, according to police.

Tiwari said up to 30 people were on the towers when the lightning struck.

"Some of the injured were left unconscious by the strikes. Others ran out in panic and extreme pain," Tiwari added.

Emergency teams were checking on Monday whether any victims had fallen into a deep moat on one side of the watchtowers.

Prime Minister Narendra Modi on Monday said special payments would be made to the families of people who lost their lives, as he offered condolences.