A UN official said on Thursday that he was “alarmed” by escalating violence in Syria’s opposition-held northwest in recent days, including airstrikes that hit near a food distribution site for displaced families and others that struck a power station and disabled water stations. The UN deputy regional humanitarian coordinator for Syria, David Carden, said in a statement that 12 civilians, including children, had been killed since Monday and the increased violence has “halted critical humanitarian activities, including services provided by 10 health facilities.” Infighting between Turkey-backed…