A gunman opened fire near the headquarters of Russia's Federal Security Service (FSB) in Moscow on Thursday evening.

State investigators later said the gunman had been killed and one FSB officer was killed on the spot. Another FSB employee died from wounds on Friday.

Four people were wounded in the shooting, the Health Ministry said. Investigators said one of the injured was a civilian.

After Thursday's shooting, police arrived and cordoned off the streets around the FSB building, which is located at Lubyanka Square in central Moscow — just a short distance from the Kremlin.

Videos of the incident posted on social media show what appear to be armed law enforcement officers running through a busy shopping area near the FSB headquarters. Channels on the Telegram messenger service published photographs, purportedly of the dead gunman with a bloodied face and a wolf's head design on his sweatshirt.

The FSB said that there was only one shooter and denied reports that he had entered the lobby of the security agency's headquarters.

Police cordoned off the area around the FSB headquarters in central Moscow after the shooting

Who was the shooter?

Russian investigators identified the shooter on Friday as 39-year-old Yevgeny Manyurov. Russian media reported he was a former private security guard who practiced shooting as a hobby.

Local media reported that the shooter used a Kalashnikov automatic weapon.

The tabloid Komsomolskaya Pravda and Ren TV channel reported that the attacker has an arsenal of firearms at home that he legally owned. The news outlets cited an investigator as their source.

According to local media, he lived in the town of Podolsk, around 40 kilometers (25 miles) south of Moscow, and was an active member of a local rifle club. He placed third at a marksmen competition in November, according to a website of a Moscow shooting club.

A neighbor told Ren TV that the alleged shooter was a "good guy, quiet, calm and well-meaning." According to Kommersant the guman became withdrawn and irritable after losing his job a few months ago.

The attack took place on Bolshaya Lubyanka street outside the FSB's headquarters

Was it a terror attack?

The FSB, which is the main successor to the Soviet-era KGB, did not immediately comment on the shooter's motives or provide further details about the security operation.

The attack took place shortly after Russian President Vladimir Putin delivered his annual press conference and while he was speaking at an event celebrating the work of Russia's security services.

Sergei Sobyanin, mayor of Moscow tweeted he was sorry for the family and friends of the dead FSB officer. He also said "thanks to the fighters of the FSB who promptly eliminated the criminal."

"This attack has shaken Moscow to its core," said DW's Emily Sherwin in Moscow. "It took place outside the FSB headquarters, an iconic building just a stone's throw away from the Kremlin. And though the motives behind the attack are not yet known, the timing is worth noting. The shooting took place just after Vladimir Putin had given his yearly press conference. The Russian president himself used to be the director of the FSB."

Reporter attacked at suspect's apartment

Russian investigators briefly detained a female reporter who visited the allleged shooter's mother. The reporter, Anna Nikitina, claims she was hit by one of the officers.

"Anna has already recorded all her injuries in the trauma center, there is a official note, and she intents to go to the Interior Ministry," said Nikita Mogutin, the acting director of Baza outlet which employees Nikitina.

dj,kmm,kp,rs/ng (dpa, Reuters, AFP, AP)

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