Mayor Anieto Olaje, 49, died on the spot from four bullet wounds, two of them in the head, according to Chief Superintendent Dionisio Coloma Jr., Eastern Visayas police director.
Witnesses said Olaje, accompanied by a certain PO1 Pinangga, his close-in bodyguard, had just arrived at the Gallera Sports Complex in Barangay San Policarpio to attend a four-cock derby at about 8:30 p.m. when the assailants casually approached the mayor and then opened fire.
As Olaje lay bloodied on the pavement, two of the attackers reportedly approached him and fired more gunshots to make sure he was killed.
The mayors bodyguard was shot in the buttocks.
Olaje was on his third and last term as mayor of Tarangnan town, some 55 kilometers from this city. His wife, Emily, is gunning for his position under the banner of the Lakas-Christian-Muslim Democrats (CMD), challenged by doctor Flordeliza Tan of the Liberal Party.
Olaje owned a fish dealing business in Calbayog City before he entered politics in 1996.
Witnesses described the mayors assailants as in their late-thirties.
Probers found four empty caliber .45 shells at the crime scene.
Coloma said investigators were still exploring all possible motives behind the killing, including politics.
Police and the Commission on Elections (Comelec) earlier declared Tarangnan town as an "immediate area of concern," along with the municipalities of Pagsanghan, Gandara and San Jorge and Calbayog City, all in the first congressional district of Samar.
Olaje was the first local executive in Samar killed in the run-up to the May 10 synchronized national and local elections.
According to unconfirmed reports, Olaje had been warned of the assassination plot and was also the target of New Peoples Army guerrillas.