Moscow: Russia said on Saturday it had arrested all four gunmen suspected of carrying out a shooting massacre in a concert hall near Moscow, and President Vladimir Putin pledged to track down and punish those behind the attack.
Militant Islamist group Daesh (Islamic State) claimed responsibility for Friday's attack, the deadliest in Russia for 20 years. But there were indications that Russia was pursuing a Ukrainian link, despite a statement from Ukrainian presidential adviser Mykhailo Podolyak that Kyiv had nothing to do with it.
The FSB security service said "all four terrorists" had been arrested while heading to the Ukrainian border, and that they had contacts in Ukraine. It said they were being transferred to Moscow.
Moscow regional governor Andrei Vorobyov said 133 bodies had been recovered from the rubble in 24 hours, and doctors were "fighting for the lives of 107 people." State TV editor Margarita Simonyan, without citing a source, had earlier given a toll of 143.
In a televised address, Putin said all four gunmen had been arrested before they had a chance to cross the border into Ukraine.
"I am speaking to you today in connection with the bloody, barbaric terrorist act, the victims of which were dozens of innocent, peaceful people," Putin said in his first public remarks since the attack.
"Terrorists, murderers, non-humans will face the unenviable fate of retribution and oblivion," said Putin, who declared Sunday, 24th March a day of national mourning across Russia.
Russia's Investigative Committee earlier said at least 115 had died in the attack, in which camouflage-clad gunmen opened fire with automatic weapons at concertgoers in the Crocus City Hall near the capital.
It said some died from gunshot wounds and others in a huge fire that broke out in the complex. Reports said the gunmen had lit the blaze using petrol from canisters they carried in rucksacks.
Bodies found in a toilet and staircase
People fled in panic. Baza, a news outlet with good contacts in Russian security and law enforcement, said 28 bodies were found in a toilet and 14 on a staircase. "Many mothers were found embracing their children," it said.
The Kremlin said FSB chief Alexander Bortnikov had reported to President Vladimir Putin that those detained included "four terrorists" and that the service was working to identify their accomplices.
The Kremlin said Putin had held conversations with the leaders of Belarus and Uzbekistan in which all sides affirmed their willingness to work together to fight terrorism.
Russian lawmaker Alexander Khinshtein said the attackers had fled in a Renault vehicle that was spotted by police in Bryansk region, about 340 km southwest of Moscow on Friday night and disobeyed instructions to stop.
He said two were arrested after a car chase and two others fled into a forest. From the Kremlin account, it appeared they too were later detained.
Khinshtein said a pistol, a magazine for an assault rifle, and passports from Tajikistan were found in the car.
Suspect interrogated
The suspect in the interrogation video was shown replying in heavily accented Russian to a series of barked questions. He said he had flown from Turkey on March 4 and had received instructions from unknown people via Telegram to carry out the attack in exchange for money.
The man was trembling throughout the questioning. He was initially shown lying on his stomach with his hands bound behind his back, his chin resting on the boot of a figure in camouflage uniform. Later he was hauled up onto his knees.
Another man with cuts and bruises to his face was shown being questioned via an interpreter while sitting on a bench with bound hands and feet.
Russia has yet to publicly present evidence of any Ukrainian link to the attack.
"Let's be straight about this: Ukraine had absolutely nothing to do with these events," Ukrainian adviser Podolyak said. "We have a full-scale, all-out war with the Russian regular army and with the Russian Federation as a country. And regardless of everything, everything will be decided on the battlefield."
One of the worst terror attacks
Five gunmen dressed in camouflage opened fire with automatic weapons at people at a concert in the Crocus City Hall near Moscow, in one of the worst such attacks on Russia in years.
Russian news reports said that the assailants threw explosives, triggering the massive blaze. Video posted on social media showed huge plumes of black smoke rising over the building, which can accommodate more than 6,000 people.
The reports said that visitors were being evacuated, but some said that an unspecified number of people could have been trapped by the blaze.
Flames leapt into the sky and plumes of black smoke rose above the venue, pictures and video showed.
Russian media reported a second blast at the venue and there were reports that some of the gunmen had barricaded themselves somewhere in the building.
'Bloody terrorist attack'
The attack took place as crowds gathered for performance by 'Picnic', a famous Russian rock band.
"Suddenly there were bangs behind us - shots. A burst of firing - I do not know what," one witness who asked not to be named told Reuters.
"A stampede began, everyone ran to the escalator," the witness said. "Everyone was screaming, everyone was running." The shooting began days after President Vladimir Putin was re-elected for a new six-year term and as Russia is prosecuting a war with Ukraine.
State news agency TASS cited Russia's Federal Security Service (FSB) as saying 40 people had been killed and more than 100 wounded.
The FSB said all necessary measures were being taken.
The Ministry expressed its sincere condolences and sympathy to the government and people of Russia, and to the families of the victims of this heinous crime, as well as its wishes for a speedy recovery for all the injured.
It was not immediately clear who the gunmen were. Russian news agencies said 70 ambulance crews had been sent to the scene.
"A terrible tragedy occurred in the shopping center Crocus City today," Moscow Mayor Sergei Sobyanin said. "I am sorry for the loved ones of the victims." Russia tightened security at airports and stations and across the capital - a vast urban area of over 21 million people. Putin has yet to comment in public.
Russia's foreign ministry said it was a "bloody terrorist attack".
"The entire world community is obliged to condemn this monstrous crime," Foreign Ministry Spokeswoman Maria Zakharova said. "All efforts are being thrown at saving people."
Shooting people
In one unverified video posted on social media, men with automatic weapons were shown firing repeatedly at screaming civilians, including women, who were cowering below what looked like an entrance sign to "Crocus City Hall".
Other video footage showed a number of people lying motionless in pools of blood outside the hall. Reuters was unable to immediately verify the footage.
Another video showed the attackers shooting at people in the concert hall.
