Attacks on police stations, churches, and a synagogue in Russia's North Caucasus republic of Dagestan have killed more than 15 police officers and many civilians. Six gunmen were also killed.
The attacks, which appeared to be organized, targeted the Orthodox cities of Derbent and Makhachkala on Pentecost. However, the attackers have not been identified so far.
Sergei Melikov, the republic's leader, stated that it was clear who was behind the assaults but did not provide any information.
The attacks on Sunday targeted two churches, a synagogue, and a police post in Makhachkala, Dagestan's main city. A priest from the Orthodox Church was among those slain.
Melikov stated that more than 15 police officers were killed. He also stated that numerous people had died, including a priest, Father Nikolai Kotelnikov, who had served in Derbent for almost 40 years.
Melikov said three days of mourning will begin on Monday.
The shooters have yet to be identified, but in a Telegram video, Melikov said that their attack was planned overseas and that Dagestan was now actively participating in Russia's conflict in Ukraine.
"We understand who is behind the organization of the terrorist attacks and what goal they pursued," he added.
Dmitry Rogozin, a prominent Russian nationalist in occupied Ukraine, cautioned that blaming every incident on "the machinations of Ukraine and NATO, this pink mist will lead us to big problems."
Social media footage shows people dressed in dark clothes firing at police cars before a convoy of rescue vehicles arrives on the site.
Gunmen assaulted a synagogue and a church in Derbent, which is home to an old Jewish population, before setting fire to both.
In Sergokal, a police car was reportedly targeted as well. Magomed Omarov, the leader of the Sergokalinsky district near Makhachkala, was detained by police after accusations surfaced that two of his sons were among those responsible for the attacks on Sunday.