More than 40 people, many of them women and children, were killed on Tuesday when the bus they were traveling in caught fire on the Firozabad-Kanpur road, about 60 km from the city of Agra in India, police said, according to Hindustan Times.

The cause of the fire was not immediately known but a senior police officer said the fire could have spread from the fuel tank. Additional Director General (law and order) Brij Lal said in Lucknow: “A tyre burst or a snapped axle caused sparks, which set the fuel tank on fire.”

Another version doing the rounds was that following a tyre burst, some LPG cylinders — kept in the bus — exploded leading to the fire.

Lal said about 55 people were on the bus and the death toll was expected to rise as some people had suffered serious burns. The private bus was on its way to Sultanpur, carrying mostly Hindu pilgrims who were returning from a weeklong religious fair in Mathura.

It took rescue officials more than two hours to douse the flames that broke out around 5.15 p.m. when the bus was near Rupakpur under Makkhanpur police station.

Firozabad SSP Navneet Rana told Hindustan Times over phone that rescuers had to use gas cutters to look for survivors inside the bus.

The injured have been rushed to SN Medical College and Hospital in Agra. The condition of six is said to be critical.

An eyewitness said the bus was overloaded. “Many passengers were sitting on the roof as well,” he said. “A few passengers saved their lives by breaking open the windows and some others jumped off the roof.”