International Desk

Russia detained four suspects as the worst terrorist attack in Moscow for more than two decades killed at least 115 people, report agencies.

Moscow pointed the finger at Ukraine after the worst terrorist attack for more than two decades.The head of Russia's Federal Security Service told President Vladimir Putin on Saturday that four people directly involved in the attack were among 11 detained, Russian state news agency Tass said.

Federal Security Service agents seized the four men in Russia's Bryansk region and alleged they planned to cross the border into Ukraine where they "had contacts," the Interfax news service reported, citing the service known as the FSB in a statement Saturday that gave no more detail."The activities of intelligence and law enforcement agencies have resulted in the detention of 11 people, including four terrorists, who directly participated in the terrorist attack on the Crocus City Hall," the FSB said in a statement.

"It has already been established that the terrorist attack was carefully planned. The weapons that the terrorists used had been placed in a cache in advance."

While the terror group ISIS has claimed responsibility for the attack—a claim the U.S. has called "credible"—the FSB alleged that "after the terrorist attack, the criminals tried to escape by car towards the Russian-Ukrainian border." Kyiv has denied any involvement in the attack.

"As a result of coordinated actions of special and law enforcement agencies, all four terrorists were detained within a few hours of each other in the Bryansk region. They are currently being transferred to Moscow."

Some Russian officials had been quick to point a finger at Ukraine in the hours after the mass shooting on Friday, including Russian Security Council Deputy Chairman Dmitry Medvedev. "If they establish that these are terrorists of the Kyiv regime, they must all be found and mercilessly destroyed. Including officials of the state that committed such atrocity," the former Russian president said of the attack.

Mykhailo Podolyak—an aide to Ukrainian President Volodymyr Zelenskyy—stated in an X post that "Ukraine had absolutely nothing to do" with the attack, and "has never resorted to the use of terrorist methods."

Medvedev was not the only Russian official to blame the mass shooting on Kyiv. Russian Parliamentary Leader Sergey Mironov also alleged that Ukraine was responsible, and accused the United States and the UK of covering up its knowledge of the attacks.

American and British intelligence agencies had issued warnings of possible extremist attacks on crowds in Russia earlier this month—and both countries did so publicly.

"All those responsible will be severely punished. I am sure that terrorists deserve the death penalty!" he said. Who are they? I have no doubt about it. Just the other day, Kiev regime leaders declared their readiness to carry out attacks on our country," Mironov said in a statement.

Unverified footage from the scene of the mass shooting, which took place at the Crocus City Hall concert hall in Krasnogorsk ahead of a rock band performance, shows crowds hiding behind their seats among the carnage. In another clip, several armed men tactical gear could be seen entering the venue, followed by the sound of rapid gunfire.

Witnesses had also reported that the gunmen—who were allegedly dressed in camouflage—threw some kind of grenade at the scene, starting a fire. Russian authorities have since said the the roof of the venue had collapsed, as investigators continue to work through the wreckage.

But the initial responses have already raised questions about how Russia might seek to blame or respond to the deadliest attack in the region for years—and whether it could be used to justify retaliation against the west or other adversaries.

Medvedev has previously suggested Ukraine should not exist and that Ukraine is undoubtedly a part of Russia.

U.S. officials have said that the State Department alert on crowds in Moscow was not intended to warn of possible threats from Ukraine, and that U.S. officials would not have referred to Ukrainians as extremists, according to The New York Times.

Russian President Vladimir Putin, for his part, brushed off the alert, accusing the west of seeking to stoke tensions inside Russia.

In any case, the fall-out from the massacre could be dire. In the wake of the 1999 apartment bombings, which left hundreds dead, Putin blamed Chechen insurgents and launched a second Chechen war.

Kremlin propagandist Vladimir Solovyov called for the death of the attackers, without pointing fingers at anyone in particular.

"The bastards who organized this do not understand the main thing—they cannot intimidate us. Death awaits terrorists—both organizers and perpetrators, no matter where they are," Solovyov said. "Every one of them."

The White House told reporters Friday that it was looking to obtain more information about the attack, with White House National Security Council John Kirby calling footage from the shooting "just horrible, and just hard to watch."

Kirby added that there is "no indication at this time that Ukraine, or Ukrainians, were involved in the shooting."