Several hundred people have gathered just outside the Kremlin walls to commemorate 40 days since the killing of a Russian opposition politician that shook the country.

Boris Nemtsov was shot on Feb. 27 as he was crossing the bridge in Moscow, just outside the Kremlin. Five suspects have been detained, but Nemtsov's allies say the mastermind of the murder is still on the loose.

Tuesday marks the 40th day since the killing and is regarded as the final commemorate date in Orthodox Christian tradition.

The bridge where Nemtsov was gunned down was packed with his supporters Tuesday morning, who brought flowers and candles to the spot where he was killed. Passing cars were honking their horns at 11 a.m. Moscow time, a designated moment of silence.