A car bomb killed a Russian general in Moscow early on Monday morning, the Investigative Committee of Russia said in a statement.

Lieutenant General Fanil Sarvarov, head of the Operational Training Directorate at the General Staff of the Russian Armed Forces, was named as the high-ranking officer killed in the explosion. He oversees combat training for Russia’s war in Ukraine.

Investigators say the possibility that the attack is linked to Ukrainian special forces is one line of inquiry.