Russia Arrests 4 Suspects in Moscow Attack as Death Toll Climbs to 133

The Russian authorities said on Saturday that they had arrested the four individuals suspected of setting a suburban Moscow concert on fire and killing at least 133 people, one of the worst terrorist attacks to jolt Russia in President Vladimir V. Putin’s nearly quarter century in power.

The Islamic State has taken responsibility for the brutal assault in three different messages issued since Friday. But Mr. Putin, in his first public remarks on the tragedy more than 19 hours after the attack, made no mention of the extremist group or the identities of the perpetrators, broadly blaming “international terrorism,” while Russian state media quickly began laying the groundwork to suggest that Ukraine and its Western backers were responsible.

The Russian leader did take a swipe at Ukraine, saying that the suspects were apprehended while traveling to the Russian border, where he alleged a crossing was being prepared for them from “the Ukrainian side.” Kyiv has denied any involvement in the attack.

Russian state news broadcasts largely ignored or cast doubt on the ISIS attribution, and commentators focused on trying to blame Ukraine. As of Saturday, the authorities had not disclosed the identities of the alleged gunmen.

But state news media did show what it described as footage of interrogations of at least two of the suspects, including one who spoke in Tajik through an interpreter and another who said he carried out the killings for money after being recruited over the messaging app Telegram. Russia’s Interior Ministry said the four suspects were all foreign citizens.

In his video address, Mr. Putin said the four main perpetrators had been apprehended, as well as seven other individuals.