A mystery weapon fell from the sky in Amhara, its effects were devastating
Missile debris also damaged the roof of a house and fell on a complex of country homes in the capital's northern Obolon district.
Four other Syrian soldiers were also wounded in the attack.
Last week witnesses and rescuers said that Russian jets bombed villages and towns near Idlib, killing at least nine civilians and wounding dozens in a major flare-up.
Air strikes and anti-aircraft missile fire hit overnight in the Omdurman and Khartoum, two of the three cities that make up Sudan's wider capital.
The United States and Saudi Arabia said the two factions had agreed to a new 72-hour ceasefire that would begin on Sunday morning.
Talks in Jeddah have failed to permanently end fighting and clashes intensified as soon as a ceasefire ended on Sunday.