A leading Russian opposition politician, former deputy Prime Minister Boris Nemtsov, has been shot dead in Moscow, Russian officials say.
An unidentified attacker shot Mr Nemtsov four times in central Moscow, a source in the law enforcement bodies told Russia's Interfax news agency.
He was shot near the Kremlin while walking with a woman, according to Russian-language news website Meduza.
"Several people" had got out of a car and shot him, it added.
Mr Nemtsov, 55, served as first deputy prime minister under the late President Boris Yeltsin in the 1990s.
He had earned a reputation as an economic reformer while governor of one of Russia's biggest cities, Nizhny Novgorod.
Falling out of favour with Yeltsin's successor, Vladimir Putin, Mr Nemtsov became an outspoken opposition politician.
He was shot in the back with a pistol from a white car which fled the scene, Interfax's source said.
One of the politician's colleagues in his RPR-Parnassus party, Ilya Yashin, confirmed Mr Nemtsov's death.
"Unfortunately I can see the corpse of Boris Nemtsov in front of me now," he was quoted as saying by Russia's lenta.ru news website. "At the Bolshoy Zamoskvoretsky Bridge. I see the body and lots of police around it."
