The number of those killed in the terrorist attack at the Crocus City Hall in the Moscow Region has risen to 143 people, Margarita Simonyan, the editor-in-chief of RT and the Rossiya Segodnya media group, said on Saturday.

"There are already more victims than in [the 2002] Nord-Ost [siege of the Dubrovka Theater in Moscow]. 143 people [killed]. Oh, God, rest their souls," Simonyan said on Telegram.

A shooting occurred on Friday evening in the Crocus City Hall concert venue in the city of Krasnogorsk, just outside Moscow, followed by a massive fire.

A Sputnik correspondent who witnessed the attack reported that at least three men in camouflage had broken into the music hall, shooting people point-blank and throwing incendiary bombs.

Eleven people were detained in connection with the attack, including four who were directly responsible, the Russian Federal Security Service (FSB) said. All four were detained in the Russian region of Bryansk, which borders Ukraine, a few hours apart, the FSB added.