Four elderly pilgrims died while riding in a non-air-conditioned train car as India's deadly heat wave continues, The Times of India reported Tuesday.

The four, aged between 69 and 81, had been returning from the holy city of Varanasi to Kerala in the south, The Independent reported. Railway official Manoj Kumar said they collapsed in their carriage and were pronounced dead by doctors waiting at the Jhansi station. The deaths come as the total number of fatalities in one of India's most intense and longest-lasting heat waves has reached at least 36, The New York Times reported Wednesday. Temperatures have soared to 50.6 degrees Celsius (123 degrees Fahrenheit), and the high temperatures are expected to impact 23 states this year, up from nine in 2015 and 19 in 2018, India's National Disaster Management Authority expert Anup Kumar Srivastava said.

#Heatwave conditions in many parts with a severe heat wave in some parts very likely over West Rajasthan; Heat wave in many parts with severe heat

wave in isolated pockets over East #Rajasthan & #MadhyaPradesh; #Heatwave to a severe heat wave in isolated pockets over UP.



IMD pic.twitter.com/fnsBgyukrg — NDMA India (@ndmaindia) June 11, 2019

"This year, the number of heat wave days [has] also increased — and it's not just day temperature, night temperatures have also been high," Srivastava told The New York Times. India has increasingly suffered from extreme heat in recent years. 2018 was the country's sixth hottest year on record, and 11 of its 15 warmest years have occurred since 2004, The Independent reported. The capital of New Delhi broke its all-time record Monday with a high of 48 degrees Celsius, according to The Times of India.