Russia observed a national day of mourning on Sunday, two days after an attack on a suburban Moscow concert hall that killed over 130 people. Events by cultural institutions were cancelled, flags lowered, and TV entertainment and advertising was suspended, according to state news agency RIA Novosti. Meanwhile, family and friends of those still missing after the attack waited for news of their loved ones. Russian President Vladimir Putin said Saturday that Russian authorities had arrested 11 suspects, including four believed to have participated in the attack. He claimed they were captured while fleeing to Ukraine. Kyiv strongly denied any involvement, and the Islamic State group’s Afghanistan affiliate claimed responsibility.