Russian investigators say they have determined who set off a deadly bomb on a St. Petersburg subway train, identifying the suspected attacker as Akbarjon Jalilov, 22.
The federal Investigative Committee made the announcement on April 4, a day after the blast that killed 14 people and injured about 50 others in Russia's second-biggest city during a visit by President Vladimir Putin.
The statement came hours after Kyrgyzstan's State Committee for National Security (UKMK) said that Jalilov, a Kyrgyz-born Russian citizen, was the main suspect in the Russian bombing.
UKMK spokesman Rakhat Sulaimanov said Jalilov was born in the southern Kyrgyz region of Osh in 1995, and that his parents were being questioned by Kyrgyz security officers there.
The Russian statement also said that investigators found "genetic traces" of Jalilov on a backpack that contained an unexploded bomb and was discovered later on April 3 at another subway station in St. Petersburg, Ploshchad Vosstania.
"Genetic testing and recordings from monitoring cameras give investigators reason to believe that the person who carried out the terrorist act in the [subway] car left the bag with the bomb at the Ploshchad Vosstania metro station," it said.
The Investigative Committee said earlier on April 4 that the bomber's remains were found in the third car of the train that was hit by the blast while traveling between two stations in the city center.
It was not immediately clear whether the suspect was being counted in the official death toll, which reached 14 on April 4.
Health Minister Veronika Skvortsova said that 49 other people remained hospitalized with injuries suffered in the blast.
Three foreigners -- from Uzbekistan, Belarus, and Tajikistan -- were among the injured, according to St. Petersburg Governor Georgy Poltavchenko.
No group has claimed responsibility for the deadliest bombing in Russia since suicide attacks on two consecutive days in December 2013 killed 34 people in the southern city of Volgograd.
St. Petersburg authorities have declared three days of mourning.
The blast badly damaged at least one subway car, and images from the scene showed dead or injured people lying on the platform after the driver brought the train into a station, while others sat stunned or tried to help the victims.
The first major bombing in Russia in more than three years, it occurred while Putin was in his home city of St. Petersburg hosting the president of Belarus.
WATCH: Chaos Inside St. Petersburg Metro Following Blast
Kremlin spokesman Dmitry Peskov said on April 4 that the bombing was a "challenge to every Russian," including Putin.
World leaders expressed condolences and solidarity, with the UN Security Council strongly condemned the "barbaric and cowardly terrorist attack."
The Kremlin said that in a telephone call on April 4, Putin, German Chancellor Angela Merkel, and French President Francois Hollande agreed to step up communications between their intelligence services in order to combat terrorism.
A Kremlin statement said the leaders "noted the importance of building up cooperation with the aim of countering the terrorist threat that is common to all countries."
There was no immediate comment from Germany or France about the call.
Russia has repeated called for closer cooperation against terrorism and accused Western governments of double standards, a charge the United States and others reject.
WATCH: Putin Reacts To St. Petersburg Blast
At an April 4 meeting with his Kyrgyz counterpart, Erlan Abdyldaev, Russian Foreign Minister Sergei Lavrov called for increased international cooperation against terrorism.
"I would like to once again express gratitude to our Kyrgyz friends and allies for again showing the importance of stepping up joint efforts to combat this evil," Lavrov said. "I'm convinced that this once again shows the importance of stepping up joint efforts to combat this evil," he said.
Lavrov said any speculation that the bombing was revenge for Moscow's military action in Syria would be "cynical and mean."
The extremist group Islamic State (IS) has called for attacks on Russia in retribution for its military intervention in Syria, where Moscow has given President Bashar-al Assad's government crucial backing throughout the six-year war and stepped up involvement by launching a campaign of air strikes in 2015.
Late on April 3, the White House said President Donald Trump telephoned Putin and offered "the full support of the United States government in responding to the attack and bringing those responsible to justice."
"Trump and President Putin agreed that terrorism must be decisively and quickly defeated," said the statement, which echoed an earlier account from Kremlin spokesman Dmitry Peskov.
Trump strongly suggested during his campaign in 2016 that he would seek to mend badly strained relations with Moscow, and expressed hope that the two countries could cooperate more closely against Islamic State and other extremist groups.
Fighting terrorism was a chief topic of a telephone conversation between Trump and Putin in late January, but there have been few signs of tangible steps toward increased cooperation.
Peskov said Trump had "extended deep condolences" to the families affected by the blast.
Many of those injured suffered shrapnel wounds, according to news reports, and law enforcement agencies said the explosive device contained up to 1 kilogram of explosives.
The blast revived grim memories of previous bomb attacks on the subway in Moscow and on trains and buses elsewhere in Russia.
Speaking to Current Time TV, St. Petersburg resident Natalya Kirillova said she was seated near the end of a subway car adjacent to the one where the explosion occurred took place.
After a "deafening explosion" that knocked seated passengers on their sides, the subway continued on to the next station and she and other passengers climbed out through the windows because the doors were broken, she said.
She saw a “huge number of people lying" on he platform.
“Bodies. It was awful," she said. "When we got out, they were pushing and pulling several people out covered in blood,” she told Current TIme, a Russian-language network run by RFE/RL in cooperation with VOA.
Bombers have struck repeatedly in Russian cities in the past two decades, with insurgents based in Chechnya -- the site of two post-Soviet separatist wars -- or other parts of the mostly Muslim North Caucasus often blamed or claiming responsibility.
The last fatal attack on a subway system in Russia occurred in Moscow in March 2010, when explosions at two stations killed at least 33 people.
There had been no major attacks in St. Petersburg.
With reporting by RFE/RL’s Kyrgyz Service, RFE/RL's Russian Service, Current Time TV, Reuters, KyrTAG, TASS, Interfax, and RIA Novosti