At least 93 people have been confirmed dead after last night's attack at Crocus City Hall in the Moscow region, according to Russia's investigative committee.
"The death toll will rise further," a statement read.
"According to preliminary data, the causes of death were gunshot wounds and poisoning by combustion products."
The committee also said that the gunmen used "flammable liquid" to set fire to the concert hall while people were still inside.
"Ballistic, genetic and fingerprint examinations are currently being carried out."
In a separate statement, the Russian department of health said at least four children were in hospital.
Additionally, state media cited regional health officials last night as saying there were three children among the dead.
As we reported earlier, at least 107 people are still in hospital.
What happened?
Last night, gunmen stormed the hall, located in the northwest suburb of Krasnogorsk.
Band Picnic were just about to play the venue, which can hold some 6,200 people.
Tickets for the older-generation Russian rock band that began performing in 1978, were sold out.
Footage shows several camouflaged gunmen walking and shooting.
Explosions were reported and a large fire broke out in the building, causing part of the roof near a theatre to collapse, but is now said to be mostly extinguished.
Suspects were still at large as of early this morning, but some 11 people have now been detained by the Russian security services, with four of those said to be "directly" involved.
Islamic State has claimed responsibility for the attack, claiming to have attacked a large gathering of Christians in Krasnogorsk on the outskirts of Moscow.
While those claims have not been independently verified, Washington said it had intelligence confirming it - and separately said it had passed all relevant information onto Moscow in recent weeks.
A senior Russian intelligence source admitted to state media that the Kremlin had received the intelligence, saying it was of a "general nature without any specifics".
This comes after the American embassy in Moscow warned about a potential attack and urged citizens to avoid large gatherings on 7 March.
Skynews