Here is the exact situation over casualty numbers
C. Victims
The exact number of victims from the Sabra and Shatila massacre is not and will never be precisely known. Estimations have always varied widely between 700 to 3500. The lowest number (between 700 and 800 victims) has been produced by the IDF and was used by the Israeli Commission of inquiry, as « this may well be the number most closely corresponding to reality » (The Kahan Commisssion, 1983). The Lebanese authorities published higher figures in the middle of October 1982. According to official sources, casualties reached the number of 2 000, and are divided as follows: 762 identified corpses have been buried by the Lebanese army or the Red Cross, whereas 1200 others have been buried by families on their own initiative and registered with the Red Cross.
The Lebanese historian Bayan al-Hout (2004) conducted fieldwork between 1982 and 1984 on casualties in Sabra and Shatila. She identified 1390 cases: 906 dead and 484 "missing".
Amnon Kapeliouk, an Israeli journalist, worked on a reconstitution of the events soon after the slaughter. He based his personal inquiry upon primary sources, such as testimonies, IDF archives and declarations, press reports, evidences gathered by the Israeli Commission of inquiry, etc. and published the results of his research in 1982: Sabra and Shatila. Inquiry Into a Massacre (Sabra et Chatila: enquéte sur un massacre], which became a reference book.
In A. Kapeliouk's opinion, the number of victims reached 3 000 - 3 500. He added to the 2000 death formally listed and recognized by the Lebanese authorities three other kinds of victims:
-* Those who were buried in mass graves dug up by the assailants and whose bodies have not been brought up;
-* Those who died under the ruins of their houses;
-* The "missing" who were taken alive to unknown destinations and never returned. According to the Red Cross, the number of the "missing" reached 359 between the 18th and the 20th of September.
No estimation of the number of injured was given, but cases of mutilation are numerous.

SOURCE

From the same source
On the morning of Friday the 17th, new Phalangists' units entered the camps. At the height of the
assault, the militiamen were about 400. The killing went on all day long with its share of summary
executions, house demolitions, and looting of private goods such as money or jewellery. Corpses
were lying on the streets, abandoned under ruins or bulldozed in mass graves. Witnesses saw many
inhabitants piled up onto trucks and driven outside the camps to unknown destinations. Nobody
knows what became of them. They are the "missing" of the Sabra and Shatila massacre.
Jim Carroll