Police said Vice Mayor Juvy Magsino, 34, had just come from the house of former town mayor Nelson Melgar in Sitio Amugis, Barangay Barcenaga when she was waylaid.
Magsino, chairman of the provincial vice mayors league, was among the local officials who welcomed President Arroyo as she campaigned in Mindoro Oriental last Friday.
Magsino was with Leima Fortu, 27, an elementary school teacher and acting secretary general in Mindoro Oriental of Karapatan, a human rights group. Fortu was also the district coordinator of the left-wing Bayan Muna party-list group.
Though wounded, Magsino was able to drive her Toyota Revo away from the scene. But the two gunmen gave chase and caught up with them about 700 meters from the ambush site.
Magsino and Fortu died from multiple gunshot wounds. Reports said police found 13 empty 9-mm shells.
Magsino was the official Lakas-CMD candidate for mayor in Naujan in the May 10 elections.
Irein Cuasay, Magsinos colleague in Karapatan, quoted her as saying that she had received at least two death threats saying she would not live beyond Feb. 15.
Magsino, a feisty human rights lawyer, was in conflict with local military commanders over alleged abuses by soldiers, including the summary execution and disappearance of suspected supporters of the communist New Peoples Army.
Magsino was the one who reportedly instigated a deeper probe of the abduction and killing of Eden Marcellana and Eduardo Gumanoy in Mindoro Oriental last year.
Marcellana chaired Karapatans Southern Tagalog chapter, while Gumanoy led the Katipunan ng mga Samahang Magbubukid sa Timog Katagalugan.
The two spearheaded a fact-finding mission on the alleged abuses of the Armys 204th Infantry Brigade then led by Col. Jovito Palparan, who is now a general. The Army unit is now headed by Col. Fernando Mesa.
Bayan Muna president Satur Ocampo condemned the killings, saying Magsino and Fortu were the 36th and 37th members of the left-wing group slain by suspected paramilitary men since it began participating in elections in 2001.
Ocampo said the manner of the killings was similar to the assassinations of other party members, suspected to have been carried out by former communist guerrillas allegedly working for the military.
"The killings of leftist candidates and personalities identified with Bayan Muna not only threaten to undermine the coming democratic electoral exercise, but also directly threatens the principle of the superiority of the civilian government over the military, as embodied in the Philippine Constitution," Ocampo said.
Sen. Robert Barbers said the Friday ambush was "unfortunate" considering that Mrs. Arroyo, along with members of her K-4 ticket, was in Mindoro Oriental that day.
Gregorio Rosal, spokesman of the Communist Party of the Philippines, said the New Peoples Army, the CPPs armed wing, would ensure that the deaths of Magsino and Fortu would be given justice.
Mesa, of the 204th IB, told radio station dzRH that the NPA might have had a hand in the killings.
"Capable sila (NPA) na gumawa ng ganyan maski sa kasangga nila (is capable of doing such a thing even to its allies) for the sake of propaganda," he said.
Magsino hosted a commentary show on radio station Radyo Natin in Naujan town, and taught at the Divine World College in Calapan City. With Mike Frialde, Christina Mendez, Benjie Villa, James Mananghaya, Jose Rodel Clapano