Afghan parliamentary deputy Dad Mohammad Khan said the casualties came in two attacks on June 18. He said most of those killed were his friends and relatives.
Five people were killed in the first attack, including a former district chief, Jama Gul, and his four bodyguards. The rest died when they went to retrieve the bodies. Among the dead was Jama Gul's brother and nephew.
The attacks happened near each other on the highway between Helmand's Sangin and Grishk districts.
Meanwhile, Afghan officials say Afghan and U.S.-led coalition forces have killed seven suspected Taliban militants and wounded four others in the southern province of Oruzgan.