UPDATE - Head of Russian nuclear protection forces killed in Moscow explosion

UPDATES WITH MORE DETAILS; EDITS THROUGHOUT

By Efe Ozkan and Burc Eruygur

ISTANBUL (AA) - Lt. Gen. Igor Kirillov, chief of Russia's Radiation, Chemical and Biological Protection Defense Troops, and his assistant were killed in an explosion in Moscow on Tuesday.

The blast was caused by an explosive device planted in an electric scooter, Svetlana Petrenko, spokesperson for the Russian Investigative Committee, said in a video statement on Telegram.

Kirillov's death came a day after Ukraine's State Security Service (SBU) charged him for allegedly ordering the "use of chemical weapons against Ukraine's Defense Forces."

"According to the investigation ... an explosive device was detonated on Ryazansky Prospekt in Moscow, which was planted in a scooter parked next to the entrance of a residential building,” Petrenko said.

The committee has launched a criminal probe into the attack, she added.

Petrenko later reported that the investigation has been placed under the category of a "terrorist attack."

Elsewhere, multiple Ukrainian media outlets, including state news agency Ukrinform, citing sources, reported that Kirillov's death came as the result of a "special operation" by the SBU.

However, Ukrainian authorities have not officially commented on the incident.