The hope for finding survivors from one of the Philippines' worst killings is fading as rescuers on Wednesday discovered three more bodies from a shallow mass grave, pushing up the death toll of Monday's massacre to 49.

Ibrahim Magundadatu, Buluan town mayor of Maguindanao province, told local television that the latest victims are all male. The bodies were unearthed from the same hillside grave in Amputuan town where 25 bodies were recovered Tuesday.

Local television network ABS-CBN reported that one of the latest massacre victims wore a "UNTV" T-shirt. The body was dug up along with a maroon Toyota Vios, which has been reported missing since Monday.

Around 100 militiamen ambushed a convoy of 51 journalists, lawyers, and supporters of Buluan town vice mayor Esmail Mangudadatu en route to register him as candidate for the provincial governor post in next year's election. They were herded away from the main road and shot or hacked to death.

National police spokesman Chief Superintendent Leonardo Espina told media that initial investigation reports indicated that the group responsible for the execution was led by the mayor of Datu Unsay -- Andal Ampatuan Jr, the arch rival of Mangudadatu in next year's provincial election. His father, Andal Ampatuan Sr, is three-time governor of Maguindanao and owns a considerable size of private army, police said.

Philippine President Gloria Macapagal-Arroyo has placed Maguindanao and two neighboring areas under the emergency rule -- which gives security forces more freedom to arrest and detain suspects. But still no arrests were made by Wednesday noon.