update: Per Reuters: "Russia’s state investigative committee said on Friday it was treating the killing of Alexander Zakharchenko, leader of Russian-backed separatists in the Donetsk region of eastern Ukraine, as an act of international terrorism."
"A criminal investigation into the killing has been opened, the committee said in its statement."
Meanwhile local reports say Zkharchenko's personal body guard is being searched for after fleeing the scene: Bodyguard may have been involved in DPR leader's murder, he disappeared after blast, he is being searched for - Source: IFX
And further, Russian President Vladimir Putin has reportedly issued a statement: "Those responsible for Zakharchenko's assassination made a dangerous choice in favor of destabilization, and attempt to put the Donbas people on their knees, but they won't succeed."
Donetsk separatist media have reported 5 people killed at the Separ cafe, the site of the blast:
According to the newspaper Vedomosti, Zakharchenko’s home is just around the corner from the Separ cafe, which is actually owned by his chief of security.
Via Meduza: The news agency Interfax reports that local police immediately apprehended several people identified as “Ukrainian saboteurs and others connected to them” who were apparently discovered in a car on Bogdan Khmelnitsky Avenue, not far from the blast site. Sources told the tabloid Life that one of Zakharchenko’s guards is also suspected of involvement in the bombing, but he managed to evade police.
Foreign Ministry spokesperson Maria Zakharova: “There is every reason to suspect that the Kyiv regime is behind his killing. More than once, it’s used similar methods to eliminate dissidents and critics.”
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According to breaking reports a targeted blast has killed Ukraine's most prominent separatist leader in what appears a high level assassination under mysterious circumstances. The head of the self-proclaimed Donetsk People’s Republic, Aleksandr Zakharchenko, was reportedly at a cafe in central Donetsk city in eastern Ukraine when an explosion of as yet unknown origin went off, killing Zakharchenko and injuring several other top separatist officials.
Local reports say that Zakharchenko was still alive at the scene, but died of his severe injuries after arriving an an area hospital.
A group of the Donetsk People’s Republic's leaders were gathered at ‘Separ’ — a well-known restaurant and cafe in the city center.
A spokesperson for the breakaway Ukrainian region confirmed his death and called it a "terrorist attack".
"The head of the DNR, Alenksandr Zakharchenko, has died as a result of a terrorist act," a spokesperson of the self-proclaimed republic’s administration told journalists, though revealed no further details of the incident.
A US broadcaster has further cited local officials to report that another separatist figure, the movement's "finance minister" Aleksandr Timofeyev, was injured in the blast at the Separ (Separatist) cafe.
Donetsk sources have yet to assign blame; however, the breakaway region in eastern Ukraine have been at war with forces loyal to the Ukrainian government in Kiev since 2014.
The heavily-armed rebels in Donetsk and Luhansk regions have waged what they say is a war for independence and have refused the the Ukrainian government in Kiev. One senior Donetsk rebel, Vladislav Berdichevsky, told Interfax news agency: "According to preliminary information, it is unfortunately true. The republic's leader suffered a fatal wound."
Local journalists and news sources circulated images of what appeared to be the blast site on social media.
And predictably, Russia’s Foreign Ministry immediately pointed the finger at Ukrainian authorities for the attack, saying Kiev had decided to engage in a “bloody fight.”
But Ukrainian security officials countered that it appears to be the work of “terrorists and their Russian sponsors.”
Lately the separatist movement has undergone internal fighting and rivalries, with several leaders reportedly having fled the region while citing unconfirmed threats by former comrades.