At least 115 people are now known to have been killed in an attack on a concert hall near Moscow, and officials are warning that the death toll could rise further. Investigators have announced a series of arrests - four people directly involved in the attack have been detained. The so-called Islamic State has claimed responsibility. Subscribe: null For more news go to: http://www.dw.com/en/ Follow DW on social media: ►Facebook: https://www.facebook.com/deutschewellenews/ ►Twitter: https://twitter.com/dwnews ►Instagram: https://www.instagram.com/dwnews ►Twitch: https://www.twitch.tv/dwnews_hangout Für Videos in deutscher Sprache besuchen Sie: null #Russia #Putin #ISIS