The death toll in the attack by Islamic militants in Russia’s southern region of Dagestan has risen to 21 after a wounded police officer has died in a hospital, officials said.

Sunday’s attack, in which militants attacked Christian and Jewish houses of worship and fired at police in the cities of Derbent and Makhachkala in the predominantly Muslim region in the North Caucasus, was the deadliest in Russia since March, when gunmen opened fire at a concert in suburban Moscow, killing 145 people.