At least six people were killed yesterday as Syrian security forces used guns and tear gas on thousands of protesters in Hama even as world powers urged Damascus to give Arab League observers full access to all parts of the country. Two people were killed in the Baba Amr district of Homs, and at least four soldiers were killed in an ambush by a group of army defectors in the south. The Syrian government yesterday released 755 prisoners detained over the past nine months. The move followed accusations by Human Rights Watch that hundreds of detainees were being hidden from League observers. The observers were due to visit Daraa, Hama and Idlib. \"As of Wednesday evening, and from Thursday at dawn, the observers will deploy in Idlib and Hama, and in Daraa,\" mission chief General Mustafa Al Dabi told AFP.