A bus fire in northwestern India has killed at least 20 people and left around 16 others seriously injured, according to local authorities and media reports.

A short circuit is thought to have sparked the fire that rapidly engulfed the vehicle, which was being driven on a major highway at the time.

What do we know about the bus fire?

The bus, carrying about 50 passengers, caught fire shortly after departing from Jaisalmer toward Jodhpur in Rajasthan state.

Witnesses said smoke began rising from the rear of the vehicle, possibly due to an electrical short circuit, before flames rapidly engulfed it.

Although the driver managed to stop the bus along the roadside near a military station, police said 19 people died at the scene and one more in the hospital.

Many victims were trapped inside because the bus had only one door for entry and exit.

"Passengers didn't get time to deboard the bus as the fire spread quickly," local ruling party lawmaker Mahant Pratap Puri told the Associated Press. 

"It was a new bus with full load of air-conditioning gas. There was just one door for entry and exit. Unfortunately, the passengers seated on the rear end couldn't make it to the exit and were burned alive," said Puri.

Prime Minister Narendra Modi expressed sorrow and announced compensation payments of 200,000 rupees ($2,200) to the families of those killed and 50,000 rupees to the injured.

Rajasthan Chief Minister Bhajan Lal Sharma also extended condolences as officials began DNA identification of the victims.

Edited by: Wesley Rahn