MOSCOW (AFP) ― A machine-gun wielding man killed an elderly nun and a parishioner while wounding six others when he opened fire during a Sunday prayer service in a cathedral in Russia’s Far East.

Russia’s second mass shooting in less than a week struck despite extraordinary security measures being taken across the vast country out of concern for possible attacks during the ongoing Winter Olympic Games in the Black Sea resort of Sochi.

A 15-year-old student shot dead a teacher and a policeman in Moscow on Monday in a school hostage drama that also left several officers injured.

Eyewitnesses to Sunday’s shooting told Russian media that the gunman had two crosses on his chest when he opened a hail of indiscriminate fire at both parishioners and the church’s icons.

Archpriest Viktor Gorbach said the nun managed to save several lives by attracting the gunman’s attention while church attendants fled for the exit in panic.

“The man burst into the cathedral when there was a fairly large number of people inside,” Gorbach told Russia’s Life News television.

“This shows that the problem of faith and prosecution against the Church is still relevant today,” he said.

The shooting occurred in the main cathedral of the South Sakhalin and Kuril Islands Archdiocese.

The impoverished Pacific region was seized by Soviet forces from Japan at the end of World War II and remains a point of intense diplomatic contention between Tokyo and Moscow.

Russian investigators identified the gunman as a 24-year-old worker at a private security firm that issued weapons to guards who protect cash-in-transit vehicles.

Such rampages are highly unusual in a country where private gun ownership remains low. Russia’s previous major incident came in April when an assailant killed six outside a hunting store in the southwestern city of Belgorod.

But the country has been on heightened security alert since 34 people were killed in two December suicide strikes in the southern hub city of Volgograd that were later claimed by guerrillas from the lawless nearby region of Dagestan.

Islamic militants who want to carve out their own state in the North Caucasus region near Sochi have threatened to disrupt the Games with attacks aimed at embarrassing Russian President Vladimir Putin.

The Games officially kicked off on Friday following the unprecedented deployment of 37,000 paramilitary troops and police in a so-called “ring of steel” around Sochi.

Some analysts note that the added protection awarded to Sochi may have left Russia dangerously exposed in other parts of the country.

But Orthodox Church Patriarch Kirill ― viewed as one of the most authoritative but also conservative figures in Russia ― blamed the violence on what he called the growing prosecution of religion by a society whose morals are becoming increasingly lax.

“They died as heroes -- like soldiers on the front line,” the patriarch said after leading prayers at the Kremlin’s ancient Cathedral of the Dormition.

“It is possible that (the gunman) was of an unsound mind. Or perhaps he simply listened too closely to all the negative things being said about the Church today,” said the patriarch.

The Church has been waging a cultural battle against its liberal critics ever since it took a tough line against the Pussy Riot punk rockers for their 2011 anti-Kremlin performance in Moscow’s main cathedral.

Two female members of the band were released under a Kremlin amnesty in December after spending nearly two years in various Russian penal colonies.