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. 0 _/ W- o& S* g& N" I- p0 A7 D 1 A K' o' `$ G9 Y# P0 VThey say they are treating it as a "terrorist incident" as they investigate.