Police say that 19 people have been killed and another 50 injured after an explosion at the Manchester Arena in northern England, where U.S. pop star Ariana Grande was giving a concert. ' Z$ [. ?* K( V: P( c0 U9 r, p u0 @$ H0 g. v8 x% l* bThey say they are treating it as a "terrorist incident" as they investigate.