Russian investigative website Conflict Intelligence Team (CIT) has reported that four members of Russia’s special forces were killed in action (KIA) in Syria on Saturday.

Makeshift memorials said that the four FSB Special Operations Center officers were killed on the same day “while performing special tasks in the Syrian Arab Republic,” with photographs of the memorials posted by the CIT on Sunday, according to a report in the Moscow Times.

The Federal Security Service’s (FSB) Special Operations Center was established by then-FSB chief Vladimir Putin as a domestic and international counterterrorism outfit in 1998, the report said.

The CIT, which said it had been investigating the FSB unit’s role in Syria, noted that it could not independently verify online reports of the officers’ deaths, the report said.

The Baza Telegram channel reported that the four officers “fell into the hands of militants” after their vehicle had hit a landmine near the northern city of Aleppo, the report said.

According to media reports, the victims were named as Major Bulat Ahmethanov, Lieut. Vsevolod Trofimov, Major Ruslan Gimadiev and Capt. Dmitry Minev.

“They were later found shot to death,” Baza, which has links in Russia’s security services, reported Monday.

Neither the FSB nor the Defense Ministry have officially confirmed or denied reports of the four officers’ alleged deaths yet, the report said.

Russia officially confirmed 116 personnel deaths in Syria as of last spring. Moscow does not acknowledge the deaths of private military contractors, whose activities are illegal under Russian law.