As four suspects were charged in the deadly terrorist attack on a concert at Moscow's Crocus City Hall, Russia's ambassador to the United States claimed that the U.S. administration didn't pass "concrete information" through the Russian Embassy in Washington about possible preparations for a terror attack.
Russian investigators said the attack killed at least 137 people, including three children, and injured 182 others. At least 101 of the victims were being treated in hospitals on Sunday, Russian officials said.
Russian authorities identified the two suspects charged in Friday's attack as Dalerjon Mirzoev and Rachabalizod Saidakrami Murodali, the press services of the Basmanny Court of Moscow told the Russian news agency Interfax on Sunday.
The suspects are charged with committing a terrorist attack that resulted in the death of a person as part of an organized group, Interfax reported. The suspects are under detention, but investigators are formally asking for their arrest.
"The court received petitions from the investigation to select a preventive measure in the form of detention in relation to Dalerjon Mirzoev and Rachabalizod Saidakrami Murodali," the press service reported.
Τhe suspects face life imprisonment if convicted.
Late Sunday and into early Monday morning local time, two other suspects were brought to the Basmanny Court – Muhammadsobir Zokirchonovich Fayzov and Shamsidin Fariduni – and charged with terrorism, according to the court. All of the suspects have been ordered to remain under pre-trial detention of at least two-months.
Meanwhile, Anatoly Antonov, the Russian ambassador to the United States, denied a statement from a U.S. State Department official Saturday that the U.S. shared information on a possible attack with Russian authorities in accordance with its longstanding "duty to warn" policy.
"Nothing was passed," Antonov told Russian state news agency TASS while answering a question about whether any information was handed over by the U.S. side before the terrorist act.
He added, "No concrete information, nothing was transferred to us."
A U.S. State Department official said Saturday that the U.S. government had shared information on a possible attack with Russian authorities in accordance with its longstanding "duty to warn" policy.
But U.S. officials claimed information sharing came ahead of Friday's deadly attack on a Moscow venue.
The search for bodies under the rubble of the Crocus City Hall, one of the largest shopping and entertainment complexes in Russia, continued on Sunday.
Russian President Vladimir Putin was informed Saturday that four suspected gunmen responsible for the attack were arrested near Russia's western border with Ukraine, Russian news agencies reported.
Seven others have been detained and the search for other accomplices is ongoing, the state news outlets reported.
ISIS claimed responsibility for the deadly attack Friday night, in which gunmen opened fire on concertgoers at one of Moscow's largest entertainment complexes. The attackers then set the complex on fire.
Antonov described the official Washington reaction to the attack on Friday as "rather muffled," adding that the administration followed on Saturday with a "clear" statement. But it was unclear how much information Washington officials had passed on prior to the attack, he said.
"The question arises whether U.S. officials passed all the available information to the Russian side, as they state," the ambassador said.
ABC News' Shannon K. Crawford contributed to this story.