The massacre lasted from the evening of Thursday 16 September to the morning of Saturday 18 September (Traboulsi gives 15-17, Hanf 17-18). The killers were militiamen of the Lebanese Forces' security service under Elie Hobeika, together with men of Saad Haddad's South Lebanon militia. The Israeli army, which controlled the area after entering West Beirut on 15 September, let them into the camps, lit the camps with flares at night and watched from command posts nearby. Israel's Kahan Commission, published on 7 February 1983, held the Phalangists directly responsible and found Defence Minister Ariel Sharon personally responsible, recommending his removal; it also attributed indirect responsibility to other Israeli political and military leaders. Estimates of the dead range from about 460-800 to 3,500; Bayan Nuwayhed al-Hout's survey found victims of twelve nationalities, about half Palestinian and more than a quarter Lebanese.

He was shot in the head 25 m from the ambassador's office, a day after the rue de Rennes attack in Paris (7 dead, 55 wounded).

Hanf (pp. 569-570): the joint US-Syrian proposal came out of three days of talks in Damascus from 15 September, after which Murphy warned the Maronite Patriarch that the alternative to Daher was chaos.