Inspector Virgilio Plaza, police chief of Giporlos town, identified the victim as Mateo Biong who sustained fatal wounds on the head and neck when he was shot at 3:50 p.m.
Biong was brought to the district hospital at the nearby town of Balangiga, where doctors declared him dead on arrival, Plaza said in a phone interview.
Plaza described the two killers as "young," and said they used a .45 caliber pistol and a 9 mm pistol in shooting the 48-year-old former mayor.
"The suspects immediately fled in the direction of Barangay Santa Cruz, an interior village," Plaza said.
Several empty shells were recovered at the crime scene at Barangay Cuticot, a kilometer away from the town proper, he added.
Biong said the police have not established the motive behind Biong's killing, but they have been checking the political angle to the attack.
The victim's son, Giporlos Mayor Mark Biong, agreed that politics could be the cause behind the shooting although he declined to explain further.
"But I am calling our police organization to help us solve the murder of my father. He was no longer in politics. Why should they kill him?" the younger Biong said in a phone interview.
Mayor Biong, who was in Manila when he was interviewed, said his father was in Cuticot to visit an ongoing project handled by their construction company.
Prior to his entry to politics in 2001, the former mayor was in the construction business.
The killing of Biong was the first slaying of a politician in Eastern Visayas after the May 10 elections. The region was described by police authorities as the "most peaceful" compared to previous elections.
Biong, who served as mayor of Giporlos town for nine years, ran unsuccessfully for the lone congressional district of Eastern Samar under the Pwersa ng Masa of deposed President Joseph Estrada.
He left behind his wife Rebecca and six children.