Thousands of people streamed to a Moscow bridge overlooking the Kremlin on Saturday to lay flowers and mark the sixth anniversary of the killing of Boris Nemtsov, a top Russian opposition figure.

Nemtsov, 55, a former deputy prime minister, was shot to death as he walked along the Bolshoi Moskvoretsky bridge late at night on Feb. 27, 2015.

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People gather on the anniversary of the death of opposition leader Boris Nemtsov in St. Petersburg, Russia, Saturday, Feb. 27, 2021. Nemtsov, a charismatic Russian opposition leader and sharp critic of President Vladimir Putin, was gunned down on Feb. 27, 2015 near the Kremlin in Moscow, Russia. (AP PhotoDmitri Lovetsky)

Thousands of people streamed to a Moscow bridge overlooking the Kremlin on Saturday to lay flowers and mark the sixth anniversary of the killing of Boris Nemtsov, a top Russian opposition figure.

A man walks to lay flowers near the place where Russian opposition leader Boris Nemtsov was gunned down, in Moscow, Russia, Saturday, Feb. 27, 2021. People gathered at the Moskvoretsky (Moscow River's) Bridge near the Kremlin in remembrance of a Russian opposition leader who was gunned down six years ago while walking on a bridge adjacent to the Kremlin. The 55-year-old Nemtsov was one of Russia's most energetic and charismatic opposition figures. His killing was a blow to forces opposing President Vladimir Putin. (AP PhotoAlexander Zemlianichenko)

Navalny's detention in January upon returning to Moscow from five months of recuperating in Germany from a nerve-agent poisoning set off a wave of nationwide protests.

People gather on the anniversary of the death of opposition leader Boris Nemtsov in St. Petersburg, Russia, Saturday, Feb. 27, 2021. Nemtsov, a charismatic Russian opposition leader and sharp critic of President Vladimir Putin, was gunned down on Feb. 27, 2015 near the Kremlin in Moscow, Russia. (AP PhotoDmitri Lovetsky)

People gather on the anniversary of the death of opposition leader Boris Nemtsov in St. Petersburg, Russia, Saturday, Feb. 27, 2021. Nemtsov, a charismatic Russian opposition leader and sharp critic of President Vladimir Putin, was gunned down on Feb. 27, 2015 near the Kremlin in Moscow, Russia. (AP PhotoDmitri Lovetsky)

Russian politician Grigory Yavlinsky lays flowers near the place where Russian opposition leader Boris Nemtsov was gunned down, in Moscow, Russia, Saturday, Feb. 27, 2021. People gathered at the Moskvoretsky (Moscow River's) Bridge near the Kremlin in remembrance of a Russian opposition leader who was gunned down six years ago while walking on a bridge adjacent to the Kremlin. The 55-year-old Nemtsov was one of Russia's most energetic and charismatic opposition figures. His killing was a blow to forces opposing President Vladimir Putin. (AP PhotoAlexander Zemlianichenko)

Russian politician Grigory Yavlinsky lays flowers near the place where Russian opposition leader Boris Nemtsov was gunned down, in Moscow, Russia, Saturday, Feb. 27, 2021. People gathered at the Moskvoretsky (Moscow River's) Bridge near the Kremlin in remembrance of a Russian opposition leader who was gunned down six years ago while walking on a bridge adjacent to the Kremlin. The 55-year-old Nemtsov was one of Russia's most energetic and charismatic opposition figures. His killing was a blow to forces opposing President Vladimir Putin. (AP PhotoAlexander Zemlianichenko)

A person walks past Russian Rosguardia (National Guard) soldiers guarding a site where people gathered on the anniversary of the death of opposition leader Boris Nemtsov in St. Petersburg, Russia, Saturday, Feb. 27, 2021. Nemtsov, a charismatic Russian opposition leader and sharp critic of President Vladimir Putin, was gunned down on Feb. 27, 2015 near the Kremlin in Moscow, Russia. (AP PhotoDmitri Lovetsky)

A person walks past Russian Rosguardia (National Guard) soldiers guarding a site where people gathered on the anniversary of the death of opposition leader Boris Nemtsov in St. Petersburg, Russia, Saturday, Feb. 27, 2021. Nemtsov, a charismatic Russian opposition leader and sharp critic of President Vladimir Putin, was gunned down on Feb. 27, 2015 near the Kremlin in Moscow, Russia. (AP PhotoDmitri Lovetsky)

Russian opposition activist and a municipal deputy of the Krasnoselsky district of Moscow Ilya Yashin, center right, lays flowers near the place where Russian opposition leader Boris Nemtsov was gunned down, in Moscow, Russia, Saturday, Feb. 27, 2021. People gathered at the Moskvoretsky (Moscow River's) Bridge near the Kremlin in remembrance of a Russian opposition leader who was gunned down six years ago while walking on a bridge adjacent to the Kremlin. The 55-year-old Nemtsov was one of Russia's most energetic and charismatic opposition figures. His killing was a blow to forces opposing President Vladimir Putin. (AP PhotoAlexander Zemlianichenko)

Russian opposition activist and a municipal deputy of the Krasnoselsky district of Moscow Ilya Yashin, center right, lays flowers near the place where Russian opposition leader Boris Nemtsov was gunned down, in Moscow, Russia, Saturday, Feb. 27, 2021. People gathered at the Moskvoretsky (Moscow River's) Bridge near the Kremlin in remembrance of a Russian opposition leader who was gunned down six years ago while walking on a bridge adjacent to the Kremlin. The 55-year-old Nemtsov was one of Russia's most energetic and charismatic opposition figures. His killing was a blow to forces opposing President Vladimir Putin. (AP PhotoAlexander Zemlianichenko)

Vladimir Kara-Murza, Russian opposition activist, center, arrives to lay flowers near the place where Russian opposition leader Boris Nemtsov was gunned down, in Moscow, Russia, Saturday, Feb. 27, 2021. People gathered at the Moskvoretsky (Moscow River's) Bridge near the Kremlin in remembrance of a Russian opposition leader who was gunned down six years ago while walking on a bridge adjacent to the Kremlin. The 55-year-old Nemtsov was one of Russia's most energetic and charismatic opposition figures. His killing was a blow to forces opposing President Vladimir Putin. (AP PhotoAlexander Zemlianichenko)

Vladimir Kara-Murza, Russian opposition activist, center, arrives to lay flowers near the place where Russian opposition leader Boris Nemtsov was gunned down, in Moscow, Russia, Saturday, Feb. 27, 2021. People gathered at the Moskvoretsky (Moscow River's) Bridge near the Kremlin in remembrance of a Russian opposition leader who was gunned down six years ago while walking on a bridge adjacent to the Kremlin. The 55-year-old Nemtsov was one of Russia's most energetic and charismatic opposition figures. His killing was a blow to forces opposing President Vladimir Putin. (AP PhotoAlexander Zemlianichenko)

A man walks to lay flowers near the place where Russian opposition leader Boris Nemtsov was gunned down, in Moscow, Russia, Saturday, Feb. 27, 2021. People gathered at the Moskvoretsky (Moscow River's) Bridge near the Kremlin in remembrance of a Russian opposition leader who was gunned down six years ago while walking on a bridge adjacent to the Kremlin. The 55-year-old Nemtsov was one of Russia's most energetic and charismatic opposition figures. His killing was a blow to forces opposing President Vladimir Putin. (AP PhotoAlexander Zemlianichenko)

A man walks to lay flowers near the place where Russian opposition leader Boris Nemtsov was gunned down, in Moscow, Russia, Saturday, Feb. 27, 2021. People gathered at the Moskvoretsky (Moscow River's) Bridge near the Kremlin in remembrance of a Russian opposition leader who was gunned down six years ago while walking on a bridge adjacent to the Kremlin. The 55-year-old Nemtsov was one of Russia's most energetic and charismatic opposition figures. His killing was a blow to forces opposing President Vladimir Putin. (AP PhotoAlexander Zemlianichenko)

Among those who attended Saturday's commemoration was Yulia Navalnaya, the wife of imprisoned Russian opposition leader Alexei Navalny.

People gather on the anniversary of the death of opposition leader Boris Nemtsov in St. Petersburg, Russia, Saturday, Feb. 27, 2021. Nemtsov, a charismatic Russian opposition leader and sharp critic of President Vladimir Putin, was gunned down on Feb. 27, 2015 near the Kremlin in Moscow, Russia. (AP PhotoDmitri Lovetsky)

People gather on the anniversary of the death of opposition leader Boris Nemtsov in St. Petersburg, Russia, Saturday, Feb. 27, 2021. Nemtsov, a charismatic Russian opposition leader and sharp critic of President Vladimir Putin, was gunned down on Feb. 27, 2015 near the Kremlin in Moscow, Russia. (AP PhotoDmitri Lovetsky)

Navalny's detention in January upon returning to Moscow from five months of recuperating in Germany from a nerve-agent poisoning set off a wave of nationwide protests.

Nemtsov was one of Russia’s most energetic and charismatic opposition figures, and his death was a blow to political opponents of President Vladimir Putin.

An officer in the security forces of Chechnya’s Kremlin-backed leader was sentenced to 20 years for firing the shots that killed Nemtsov. Four other men were sentenced to 11 to 19 years for involvement.

A man walks to lay flowers near the place where Russian opposition leader Boris Nemtsov was gunned down, in Moscow, Russia, Saturday, Feb. 27, 2021. People gathered at the Moskvoretsky (Moscow River's) Bridge near the Kremlin in remembrance of a Russian opposition leader who was gunned down six years ago while walking on a bridge adjacent to the Kremlin. The 55-year-old Nemtsov was one of Russia's most energetic and charismatic opposition figures. His killing was a blow to forces opposing President Vladimir Putin. (AP PhotoAlexander Zemlianichenko)

A man walks to lay flowers near the place where Russian opposition leader Boris Nemtsov was gunned down, in Moscow, Russia, Saturday, Feb. 27, 2021. People gathered at the Moskvoretsky (Moscow River's) Bridge near the Kremlin in remembrance of a Russian opposition leader who was gunned down six years ago while walking on a bridge adjacent to the Kremlin. The 55-year-old Nemtsov was one of Russia's most energetic and charismatic opposition figures. His killing was a blow to forces opposing President Vladimir Putin. (AP PhotoAlexander Zemlianichenko)

People gather on the anniversary of the death of opposition leader Boris Nemtsov in St. Petersburg, Russia, Saturday, Feb. 27, 2021. Nemtsov, a charismatic Russian opposition leader and sharp critic of President Vladimir Putin, was gunned down on Feb. 27, 2015 near the Kremlin in Moscow, Russia. (AP PhotoDmitri Lovetsky)

People gather on the anniversary of the death of opposition leader Boris Nemtsov in St. Petersburg, Russia, Saturday, Feb. 27, 2021. Nemtsov, a charismatic Russian opposition leader and sharp critic of President Vladimir Putin, was gunned down on Feb. 27, 2015 near the Kremlin in Moscow, Russia. (AP PhotoDmitri Lovetsky)

Russian politician Grigory Yavlinsky lays flowers near the place where Russian opposition leader Boris Nemtsov was gunned down, in Moscow, Russia, Saturday, Feb. 27, 2021. People gathered at the Moskvoretsky (Moscow River's) Bridge near the Kremlin in remembrance of a Russian opposition leader who was gunned down six years ago while walking on a bridge adjacent to the Kremlin. The 55-year-old Nemtsov was one of Russia's most energetic and charismatic opposition figures. His killing was a blow to forces opposing President Vladimir Putin. (AP PhotoAlexander Zemlianichenko)

Russian politician Grigory Yavlinsky lays flowers near the place where Russian opposition leader Boris Nemtsov was gunned down, in Moscow, Russia, Saturday, Feb. 27, 2021. People gathered at the Moskvoretsky (Moscow River's) Bridge near the Kremlin in remembrance of a Russian opposition leader who was gunned down six years ago while walking on a bridge adjacent to the Kremlin. The 55-year-old Nemtsov was one of Russia's most energetic and charismatic opposition figures. His killing was a blow to forces opposing President Vladimir Putin. (AP PhotoAlexander Zemlianichenko)

A person walks past Russian Rosguardia (National Guard) soldiers guarding a site where people gathered on the anniversary of the death of opposition leader Boris Nemtsov in St. Petersburg, Russia, Saturday, Feb. 27, 2021. Nemtsov, a charismatic Russian opposition leader and sharp critic of President Vladimir Putin, was gunned down on Feb. 27, 2015 near the Kremlin in Moscow, Russia. (AP PhotoDmitri Lovetsky)

A person walks past Russian Rosguardia (National Guard) soldiers guarding a site where people gathered on the anniversary of the death of opposition leader Boris Nemtsov in St. Petersburg, Russia, Saturday, Feb. 27, 2021. Nemtsov, a charismatic Russian opposition leader and sharp critic of President Vladimir Putin, was gunned down on Feb. 27, 2015 near the Kremlin in Moscow, Russia. (AP PhotoDmitri Lovetsky)

Russian opposition activist and a municipal deputy of the Krasnoselsky district of Moscow Ilya Yashin, center right, lays flowers near the place where Russian opposition leader Boris Nemtsov was gunned down, in Moscow, Russia, Saturday, Feb. 27, 2021. People gathered at the Moskvoretsky (Moscow River's) Bridge near the Kremlin in remembrance of a Russian opposition leader who was gunned down six years ago while walking on a bridge adjacent to the Kremlin. The 55-year-old Nemtsov was one of Russia's most energetic and charismatic opposition figures. His killing was a blow to forces opposing President Vladimir Putin. (AP PhotoAlexander Zemlianichenko)

Russian opposition activist and a municipal deputy of the Krasnoselsky district of Moscow Ilya Yashin, center right, lays flowers near the place where Russian opposition leader Boris Nemtsov was gunned down, in Moscow, Russia, Saturday, Feb. 27, 2021. People gathered at the Moskvoretsky (Moscow River's) Bridge near the Kremlin in remembrance of a Russian opposition leader who was gunned down six years ago while walking on a bridge adjacent to the Kremlin. The 55-year-old Nemtsov was one of Russia's most energetic and charismatic opposition figures. His killing was a blow to forces opposing President Vladimir Putin. (AP PhotoAlexander Zemlianichenko)

Vladimir Kara-Murza, Russian opposition activist, center, arrives to lay flowers near the place where Russian opposition leader Boris Nemtsov was gunned down, in Moscow, Russia, Saturday, Feb. 27, 2021. People gathered at the Moskvoretsky (Moscow River's) Bridge near the Kremlin in remembrance of a Russian opposition leader who was gunned down six years ago while walking on a bridge adjacent to the Kremlin. The 55-year-old Nemtsov was one of Russia's most energetic and charismatic opposition figures. His killing was a blow to forces opposing President Vladimir Putin. (AP PhotoAlexander Zemlianichenko)

Vladimir Kara-Murza, Russian opposition activist, center, arrives to lay flowers near the place where Russian opposition leader Boris Nemtsov was gunned down, in Moscow, Russia, Saturday, Feb. 27, 2021. People gathered at the Moskvoretsky (Moscow River's) Bridge near the Kremlin in remembrance of a Russian opposition leader who was gunned down six years ago while walking on a bridge adjacent to the Kremlin. The 55-year-old Nemtsov was one of Russia's most energetic and charismatic opposition figures. His killing was a blow to forces opposing President Vladimir Putin. (AP PhotoAlexander Zemlianichenko)

A man walks to lay flowers near the place where Russian opposition leader Boris Nemtsov was gunned down, in Moscow, Russia, Saturday, Feb. 27, 2021. People gathered at the Moskvoretsky (Moscow River's) Bridge near the Kremlin in remembrance of a Russian opposition leader who was gunned down six years ago while walking on a bridge adjacent to the Kremlin. The 55-year-old Nemtsov was one of Russia's most energetic and charismatic opposition figures. His killing was a blow to forces opposing President Vladimir Putin. (AP PhotoAlexander Zemlianichenko)

A man walks to lay flowers near the place where Russian opposition leader Boris Nemtsov was gunned down, in Moscow, Russia, Saturday, Feb. 27, 2021. People gathered at the Moskvoretsky (Moscow River's) Bridge near the Kremlin in remembrance of a Russian opposition leader who was gunned down six years ago while walking on a bridge adjacent to the Kremlin. The 55-year-old Nemtsov was one of Russia's most energetic and charismatic opposition figures. His killing was a blow to forces opposing President Vladimir Putin. (AP PhotoAlexander Zemlianichenko)