In this video grab, Russian Federal Security Service operatives detain a man outside Moscow on Sept. 30, 2017.

MOSCOW, July 15 (Xinhua) -- Russia's Federal Security Service (FSB) said Monday that it had prevented activities of a cell of the Islamic State (IS) terrorist group in the country's southern Rostov region.

The cell comprised three Russian citizens who were preparing attacks on police officers and terrorist acts on public places with many people, according to a FSB statement.

The leader of the group was killed while offering armed resistance, and the other two members were detained, the statement said.

Russia's investigating authorities have instituted a criminal proceeding on the incident and necessary investigative and operational measures are underway.