Two Russian servicemen were killed and a third wounded in a mortar attack in Syria, the Russian Defense Ministry announced Tuesday.

“Russian professional servicemen who were in a unit of Syrian forces as instructors … came under a mortar attack from a group of rebel fighters,” the Defense Ministry said in a statement quoted by Interfax news agency.  “As a result of a mortar explosion, two Russian servicemen died.”

A third officer was badly wounded.

The soldiers were embedded with a Syrian army unit along with a Russian military adviser.

The ministry did not specify when or where the attack took place.

This incident brings the Russian death toll in Syria to 29, according to the ministry.