Two women have died following an explosion on a bus in western Russia that also left 17 people injured. The explosion went off overnight Thursday when the bus carrying 35 passengers was at a stop near a shopping center.

“The number of injured has risen to 19”, - the governor of Voronezh region Alexander Gusev said.

One woman died shortly after the explosion and another passed away in hospital on Friday morning, according to Gusev. Several of the wounded remain in serious condition, the governor said.

Video taken by passersby and posted on social media showed that the blast tore the roof off the vehicle and blew out its windows.

The Voronezh branch of the Investigative Committee, which probes major crimes, said Friday that it had opened a negligence case over the upkeep of the bus.

It added that experts from Moscow have been sent to Voronezh to help establish the circumstances of the explosion.

Voronezh deputy governor Sergei Sokolov had earlier told the Interfax news agency that there was “nothing to indicate that this was a terrorist attack”.

Road accidents are frequent in Russia due to the poor state of road infrastructure and a relaxed attitude towards rules of the road, particularly driving under the influence.