Sources told Al-Jazeera that 15 soldiers of the Fifth Legion of the Syrian regime forces were killed by an explosion targeting their bus in the eastern Daraa countryside, which is the legion established by Russia.

The sources added that the targeting of the bus near the town of Kahil, east of Daraa, also resulted in a large number of injuries.

The sources pointed out that the dead were members of the opposition who joined the Fifth Corps - which is directly run by Russian forces - after the settlement agreement that was held between the opposition and the regime in mid-2018.

The Syrian Observatory for Human Rights said that the accident was caused by the explosion of an explosive device planted at the side of the road and detonated remotely, indicating that the explosion left 19 wounded, some of them in serious conditions.

The regime had recovered Daraa, the cradle of the 2011 uprising, from the hands of the opposition factions in the summer of 2018, with support from Moscow.

The forces of the regime are under attack, and no one has announced them. In early May, unidentified gunmen kidnapped 9 police officers, before they were executed by shooting them, according to the observatory.