Russian authorities detained 11 people, state media reported Saturday, after gunmen stormed a concert hall in Moscow in a grisly attack that left at least 115 people dead. Russia's Investigative Committee said four of those detained were directly involved in the attack that left the sprawling shopping mall and music venue smoldering with a collapsed roof. Russian agencies appeared to suggest the attack was linked to Ukraine even though the Islamic State group claimed responsibility in a statement. A U.S. intelligence official told The Associated Press that U.S. agencies had confirmed that that group was responsible for the attack. The...