Well-known Russian military blogger Vladlen Tatarsky was killed in a blast at a cafe in the Russian city of St. Petersburg on Sunday, Russia's Interior Ministry said.
The state Investigative Committee said 19 other people were wounded and that it had opened a murder investigation.
"One person was killed in the incident. He was military correspondent Vladlen Tatarsky," the Interior Ministry said.
The explosion took place at the Street Food Bar No. 1 cafe that had reportedly at one time belonged to Yevgeny Prigozhin, founder of the Wagner mercenary group that is fighting for Russia in Ukraine.
Who was the Russian blogger?
Tatarsky, whose real name is Maxim Fomin, had reportedly invited people to a "patriotic evening" event hosted by Cyber Front Z, a group that refers to itself as "Russia's information troops."
"There was a terrorist attack. We took certain security measures, but unfortunately, they were not enough," the group said on Telegram.
Russia's TASS news agency quoted a law enforcement source saying the blast was "caused by an improvised explosive device hidden inside a statue given to Tatarsky as a gift."
It was not immediately clear who was behind the blast. The Interior Ministry said everyone inside the cafe at the time of the incident was being "checked for involvement."
Russia points finger at Ukraine, Ukraine at 'domestic terrorism' in Russia
Russian Foreign Ministry condemned the attack in a statement, with spokesperson Maria Zakharova saying bloggers like Tatarsky were regularly threatened by Kyiv.
Zakharova said that the lack of a reaction from western governments "speaks for itself given their ostensible concern for the well-being of journalists and freedom of expression."
This appeared to be a reference to American journalist Evan Gershkovic, who was arrested and accused of spying earlier this week on charges his employer and the US government have rejected as absurd.
Meanwhile, Mykhailo Podolyak, a top adviser to Ukrainian President Volodymyr Zelenskyy, wrote in English online that he believed the attack was domestic terrorism in Russia.
"Spiders are eating each other in a jar. Question of when domestic terrorism would become an instrument of internal political fight was a matter of time Podolyak wrote.
Tatarsky supportive but sometimes critical of Russian campaign
Tatarsky had reported from the Ukraine frontline and even attended a lavish Kremlin ceremony last September to proclaim Russia's illegal annexation of four partly occupied regions of Ukraine.
Originally from Donbas in eastern Ukraine, he was one of the most prominent of the influential military bloggers who have backed Russia's war effort.
Although he was a vocal supporter of the war, he also criticized some aspects of the Russian campaign.
He had more than 560,000 followers on Telegram.
If Tatarsky was deliberately targeted, it would be the second assassination on Russian soil of a high-profile figure associated with the war.
Russia's Federal Security Service accused Ukraine's secret services last August of killing Darya Dugina, the daughter of an ultra-nationalist, in a car bomb attack near Moscow. But Ukraine denied involvement.
