At least eight people have been killed and 56 injured in an explosion on a bus in the Russian city of Tolyatti.
The governor of Russia's southern Samara province said the incident was being treated as terrorism.
The early morning explosion on the bus, which came as people travelled to work in the rush hour, was probably caused by about 1kg of explosives.
The force of the blast at a road junction blew out the windows of a nearby residential block.
Tolyatti has a population of about 700,000 people and is the centre of the Russian car industry.
It was the second blast on a bus in Russia in just over a week, following an explosion that killed one person and wounded five in the turbulent province of Dagestan on 23 October.
