9 detained in Tajikistan in relation to Moscow concert hall attack, Russian state media report The Associated PressRussia arrests another suspect in concert hall attack that killed 143 The Associated PressTajikistan detains 9 people over Russian concert hall attack – source ReutersNine detained in Tajikistan in relation to Moscow concert hall attack Al Jazeera EnglishKremlin Treads Carefully After Moscow Attack Over Fears of Ethnic Strife The New York Times