The heroic British troops refused to abandon the family after seeing one adult had been killed and a young girl was badly hurt, the Daily Starreported.
But as they treated the girl, the patrol reportedly came under attack from ISIS extremists.
The Brit troops were forced to withdraw to an abandoned compound and they fought off the jihadis for a gruelling six hours.
“The one chance the SBS guys had was to last until nightfall and then they would have the advantage because of their night-vision equipment,” a source told the paper.
When they had cover of darkness, the elite British troops tricked the ISIS jihadis into thinking they were in another position.
The patrol team then reportedly fled to safety along with the injured girl who made a full recovery.
The SBS troops had been on a joint patrol with Afghan special forces in eastern Afghanistan when they were ambushed.