At least eight people were killed and 45 injured Wednesday morning in a suspected terrorist blast on a city bus in central Togliatti, a city on Russia's Volga River in Samara Region.
A spokesman for the regional police department said an explosive device equivalent to one kilogram of TNT, with no solid encasement, had been discovered fastened to underside of the bus, Russian news agencies reported.
Governor of the Samara Region Vladimir Artyakov said a criminal case has been filed to investigate the explosion as ''a terrorist attack''.
Andrei Derbenev, a spokesman for the city's rescue service, earlier said 20 people had been hospitalised, of these two were in a critical condition.
The death toll was expected to rise, TV reports said, adding several others also sought medical help.
''Many of them were a long way from the bus at the time of the blast, but were hit by fragments. The shockwaves smashed windows on the ground and first floor of a nearby building,'' reports added.
The explosion took place in the central part of Togliatti at 0812 hrs local time, on the crossroads of the Marx Street and Gagarin Street (according to other reports, the Maxim Gorky Street), near the Cosmos bus stop.
Togliatti, with a population of about 700,000 people, is home to Russia's largest auto major Avto Vaz, which produces cars under the Lada brand.
''Specialists are examining various versions of where the explosive device was laid. Probably, one of the passengers was carrying it, or it was laid, when the bus was on the way,'' an investigation official, on the spot, told Itar-Tass news agency.