A senior Russian general was killed Tuesday by a bomb hidden in a scooter outside his apartment building in Moscow, a day after Ukraine’s security service leveled criminal charges against him. A Ukrainian official said the service carried out the attack.

Lt. Gen. Igor Kirillov, the chief of the military’s nuclear, biological and chemical protection forces, was killed as he left for his office. Kirillov’s assistant also died in the attack.

Kirillov, 54, was under sanctions from several countries, including the U.K. and Canada, for his actions in Moscow’s war in Ukraine. On Monday, Ukraine’s Security Service, or SBU, opened a criminal investigation against him, accusing him of directing the use of banned chemical weapons.

An official with the SBU said the agency was behind the attack. The official, who spoke on condition of anonymity because they were not authorized to release the information, described Kirillov as a “war criminal and an entirely legitimate target.”

The SBU has said it recorded more than 4,800 occasions when Russia used chemical weapons on the battlefield since its full-scale invasion in February 2022. In May, the U.S. State Department said that it had recorded the use of chloropicrin, a poison gas first deployed in World War I, against Ukrainian troops.