Former Russian deputy prime minister Boris Nemtsov has been shot dead in Moscow.
The 55-year-old was shot four times by an unidentified attacker near the Kremlin, according to the Interfax news agency. He was reportedly shot near the Kremlin while walking with a woman.
Russian-language news website Meduza reported that "several people" got out of a white car and shot him in the back with a pistol. The attackers then fled the scene.
One of the politician's colleagues in his RPR-Parnassus party, Ilya Yashin, confirmed Mr Nemtsov's death saying: "Unfortunately I can see the corpse of Boris Nemtsov in front of me now. At the Bolshoy Zamoskvoretsky Bridge. I see the body and lots of police around it."
Garry Kasparov, chairman of the Human Rights Foundation, said: "Devastated to hear of the brutal murder of my long-time opposition colleague Boris Nemtsov. Shot four times, once for each child he leaves.
"Boris's quality no longer fit Putin's Russia. He always believed Russia could change from inside without violence; after 2012 I disagreed. When we argued, Boris would tell me I was too hasty, that in Russia you had to live a long time to see change. Now he'll never see it. RIP."
Mr Nemtsov 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.
Mr Nemtsov was a critic of Vladimir Putin's administration and had planned to attend an "anti-crisis march" through the capital on Sunday.