MOSCOW - A Russian lieutenant general and his assistant were killed by an explosion in a Moscow residential building on Tuesday morning.

Lieutenant General Igor Kirillov, head of the Russian Armed Forces' radiological, chemical and biological defense troops, was killed in the explosion, said the Russian Investigative Committee.

Preliminary information showed the explosion occurred after the detonation of an explosive device, which had a power of about 200 grams of TNT.

The explosive device was planted in a scooter, said the committee, adding that a criminal case has been opened in connection with the killing.