Bloomberg via Getty ImagesAn explosion outside a major train station in Moscow that killed a traffic police officer and injured two others was a suicide attack, Russian officials say.
Russia's Interior Ministry said the officers had been patrolling at Savyolovsky Station Square, north of the city centre, when "an unidentified device was detonated" in the early hours of Tuesday.
The Russian Investigative Committee identified the suspect as a 22-year-old man from the country's Udmurt republic, adding that an investigation was under way.
A motive has not yet been established. Russian President Vladimir Putin said the suspect was apparently recruited online.
Putin told a meeting of Russia's domestic spy agency that terror attacks had been increasing, mostly at the hands of Ukrainian intelligence.
However, attacks attributed to Ukraine in Russia have typically not involved suicide bombings.
Putin claimed the suspect in the attack, which occurred just after midnight local time (21:05 GMT on Monday), had been blown up remotely.
Russian Investigative Committee spokeswoman Svetlana Petrenko said the attacker - who she said was a Russian native - had travelled from St Petersburg to Moscow by train on Sunday.
She said the committee was now looking into a motive for the attack and whether he had any accomplices.
The perpetrator and the police officer both died at the scene, Petrenko added.
Officials have given no additional information regarding the explosive device so far.
The attacker approached officers from the north-eastern district of Moscow, the Interior Ministry said in a statement.
A criminal case has been opened against the perpetrator for the attempt on the life of a law enforcement officer and charges relating to the explosive device.
Law enforcement agencies were working in tandem to "establish all the circumstances", the ministry added.
The two injured officers were taken to hospital "with various injuries" following the explosion.
Medical sources told news agency Tass the officers were in a serious condition.
The ministry identified the officer who was killed as 34-year-old Police Lieutenant Denis Bratuschenko, a senior inspector in the traffic police.
He had joined the force in 2019 and is survived by his wife and two children, it said.
"The leadership and personnel of the Ministry of Internal Affairs of Russia express their sincere condolences to the family," a statement from Irina Volk, the ministry's spokeswoman, read.
This is not the first time traffic police have been killed in an explosion in the Russian capital.
In December, two officers died after an explosive device was detonated when they approached a "suspicious individual" to detain him.
