In Switzerland, a bus caught fire in the town of Kerzers last evening, killing six people and severely injuring three others.
Police spokesperson Frederic Papaux said an unspecified voluntary act could have caused the fire.
Police said that ambulance and helicopter teams ferried three injured people with severe injuries to hospitals, while two others were treated on site. An investigation is underway.
The incident took place on Tuesday night in the town of Kerzers – known in French as Chiètres – in Fribourg canton, about 20km (12 miles) from the capital, Bern.
Officials said on Wednesday that a survivor told them a Swiss man in his 60s had sprayed a flammable liquid on his body before setting himself on fire. He is thought to be among the dead.
Fribourg’s general prosecutor said the man appeared to be “psychologically unstable”, adding: “There is absolutely no evidence to suggest that this was a terrorist act.”