- U.N. special envoy says Syrian opposition groups want immediate reduction in violence
- He'll meet Tuesday in Geneva with Syrian government representatives
- More than 300,000 people -- including many civilians -- have died in Syria's civil war
Geneva, Switzerland (CNN)Warring sides of Syria's gruesome war are meeting in Geneva in hopes of ending the bloodshed, such as a Sunday triple bombing near a suburb in Damascus that killed dozens. ISIS claimed responsibility.