Attacks on churches in Chechnya are rare. There are not many churches in the region, and they are protected by Mr. Kadyrov’s forces.
The attack comes as Russia prepares to host the World Cup next month. No games will be played in Grozny, but it will serve as the training ground for the Egyptian team. Russian news outlets reported in April that the Federal Security Bureau — the country’s main security agency — said that it had thwarted a series of terrorist attacks planned for the World Cup in the Moscow area.
At least one of the suspected gunmen had been identified as a resident of a suburb of Grozny, Mr. Kadyrov said, but provided no further details on any of the attackers.
A 2014 attack in central Grozny killed at least 20, and a deadly 2017 attack on the Russian military, also in Grozny, was linked to the Islamic State.
Islamist extremists have struck other parts of Russia as well in recent years, and have previously targeted churches. In the neighboring region of Dagestan earlier this year, a man opened fire on worshipers at an Orthodox church, killing at least five people. The Islamic State claimed responsibility.
Twin attacks in 2013 in Volgograd killed at least 34 people. A 2017 attack in St. Petersburg left at least 11 people dead and was later claimed by Al Qaeda. Both cities will be hosting games in this summer’s World Cup.