MOSCOW (AP) — Russia’s southern region of Dagestan is holding the first of three days of mourning following a rampage by Islamic militants that killed 19 people, most of them police, and attacked houses of worship in apparently coordinated assaults in two cities. Sunday’s violence was the latest that officials blamed on Islamic extremists in the predominantly Muslim region in the North Caucasus. It also was the deadliest in Russia since March, when gunmen gunmen opened fire at a concert in suburban Moscow, killing 145 people. That attack was claimed by an affiliate of the Islamic State group. but no group has taken responsibility for Sunday’s attacks in Dagestan’s cities of Makhachkala and Derbent. All five gunmen were reported killed.