Before Attack in Russia, a 'Secret Warning' From the US

As authorities try to piece together what happened at a mass shooting at Moscow's Crocus City concert hall on Friday that left more than 100 dead and close to 150 injured, at last count, the Wall Street Journal reports on a "secret warning" that was sent from the US to Russia earlier this month on possible attacks in large crowds. On March 7, the US Embassy in Moscow is said to have cautioned American citizens in Russia to steer clear of concert venues or other places where large gatherings take place, due to intel about a planned terrorist attack. A National Security Council rep says the US "also shared this information with Russian authorities in accordance with its long-standing 'duty to warn' policy." Putin's response, per the Tass news agency: He called the warnings from his adversary "provocative," as well as "outright blackmail and an intention to intimidate and destabilize our society." More on the shooting:

• Death toll update: Per the New York Times, there are now 115 dead, including children, with at least 145 injured. "The number of dead will still rise," Russia's Investigative Committee says in a statement.
• Arrests: On Saturday morning, Russian officials announced that 11 people had been detained in connection with the attack, including four gunmen, reports CBS News. The suspects were reportedly nabbed in the Bryansk region of western Russia, "not far from the border with Ukraine," per the committee.
• Behind the shooting: The Islamic State has claimed responsibility for the attack, and US officials believe it was carried out by ISIS-K, a branch of the terrorist group that mainly operates in Afghanistan, Iraq, and Pakistan.
• Finger-pointing from Putin? Still, the Russian leader on Saturday suggested that Ukraine was behind the attack, per the AP and Moscow Times. Putin said the suspects were caught on their way back to Ukraine. His domestic intelligence agency, the FSB, has echoed that insinuation, noting the attackers had planned to flee to Ukraine and "had contacts on the Ukrainian side," per the Times. Putin noted that Sunday would be designated as a day of mourning in Russia.

(More Russia stories.)