According to the UK-based Syrian Observatory of Human Rights, the aerial attack took place on a cave where the headquarter of the Fursan al Haq was located in Homs province but its collapse made it impossible to know the fate of those trapped inside.
Fursan al Haq is the opposition faction of the Syrian Free Army, Efe news reported.
The rescue teams encountered serious difficulties clearing the rubble due to the ongoing bombing sorties by the air force.
The Syrian Army indicated that "a number of terrorists" were dead or wounded after the bombing operations.
The troops also destroyed four rebel tanks and three vehicles equipped with heavy machine guns.
