In 1979 Islamic militants seized control of the Grand Mosque in Mecca, the holiest site in Islam. Hundreds were killed as Saudi security forces battled for two weeks to retake the shrine. The militants were ultra-conservative Sunni Muslims who believed that the Mahdi, the prophesied Redeemer, had emerged and was a member of their group. The BBC's Eli Melki spoke to eyewitnesses who were inside the Grand Mosque during the siege.