Lieutenant General Igor Kirillov is the head of the Troops of Radiological, Chemical and Biological Defense of the Russian armed forces.

According to Russian media reports, Kirillov's assistant was killed in the blast.

The explosive device was reportedly placed in an electric scooter.

"According to the investigation, on the morning of December 17, an explosive device, planted in a scooter parked next to the entrance of a residential building, was detonated on Ryazansky Prospekt in Moscow. As a result of the incident, the head of the radiation, chemical and biological defense troops of the armed forces of Russia, Igor Kirillov, and his assistant were killed," Russian Investigative Committee wrote on Telegram as quoted by Sputnik news agency.

A criminal case has been registered in connection with the incident.

As per a Ukrainian newspaper report, Kirillov's death was part of a special operation carried out by Ukraine’s Security Service (SBU).

“Kirillov was a war criminal and a legitimate target. He was responsible for ordering the use of prohibited chemical weapons against Ukrainian forces,” an SBU source told Kyiv Post.

“This is the fate awaiting all those who kill Ukrainians. Retribution for war crimes is inevitable,” the source told Kyiv Post," the source said.