Nine days before he was to take office, on 14 September 1982, Bachir was killed along with 25 others in a bomb explosion in the Kataeb headquarters in Achrafieh. The attack was carried out by Habib Shartouni, a member of the Syrian Social Nationalist Party (SSNP), believed by many to have acted on instructions of the Syrian government of President Hafez al-Assad. The next day, Israel moved to occupy the city, allowing Phalangist members under Elie Hobeika's command to enter the centrally located Sabra and the Shatila refugee camp; a massacre followed, in which Phalangists killed between 762 and 3,500 (number is disputed) civilians, mostly Palestinians and Lebanese Shiites, causing great international uproar. Many cite the massacre as revenge for the killing of Bachir Gemayel and the countless massacres committed by the PLO against the Christian civilian population since 1975.