Tajikistan has detained nine people this week suspected of having links to a mass shooting at a Russian concert hall last Friday and also to the militant Islamist group that claimed responsibility, a Tajik security source told Reuters. Four suspected gunmen behind the deadliest attack in Russia in 20 years are Tajik citizens. Tajikistan's state security committee detained nine people on Monday in the city of Vakhdat and the suspects are now in the capital, Dushanbe, the source said, without providing any further details.