Six people died and at least four were injured in a fire on a bus traveling on a regular route in western Switzerland, police reported last night, quoted by DPA.
Three of the injured are in critical condition, police in the canton of Fribourg said. An ambulance worker was also injured in the rescue operation.
The accident took place in the municipality of Kerzers, west of the capital Bern.
"It is possible that deliberate actions were the cause of this tragedy," police said, adding that the flames may have been deliberately lit.
When asked to comment on whether it could be a terrorist act, a police spokesman said at a press conference that it was too early to say.
The Swiss newspaper "Blick" quoted an eyewitness as saying that a man poured gasoline on the bus and then set himself on fire. The police indicated that similar information had been reported to them, but added that they could not confirm it at this time.
Videos were shared on social media showing the vehicle engulfed in flames and thick smoke rising into the sky.
Firefighters extinguished the fire, but the bus was completely burned to the ground. The video footage shows a number of passersby filming the burning vehicle with their mobile phones.
Law enforcement authorities cannot yet say how many passengers were on the bus, nor whether the driver was among the victims. The identification of the bodies is underway. It is also unclear whether the person who may have started the fire is among the dead.
The bus is owned by "Postauto" (PostAuto), a subsidiary of Swiss Post, mainly providing scheduled passenger transport in rural areas.