A bomb hidden in an electric scooter killed a senior Russian general in charge of nuclear protection forces in Moscow on Tuesday, Russia’s investigative committee said.

Lieutenant General Igor Kirillov, who is chief of Russia’s Nuclear, Biological and Chemical Protection Troops, was killed outside an apartment building on Ryazansky Prospekt, which starts road some 7 km (4.35 miles) southeast of the Kremlin.

“Igor Kirillov, the head of the radiation, chemical and biological protection forces of the armed forces of the Russian Federation, and his assistant were killed,” the investigative committee said.

A criminal case has been opened.