Prior to the ambush, Senior Superintendent James Melad, Cagayan police director, said Mayor Ramon Nolasco had received death threats from political enemies whom he refused to name.
"From the information gathered by our investigators, it appears that politics was behind the ambush," said Nolasco, former intelligence and investigation chief of the regional police.
He said a number of political personalities, whom he refused to identify, are now being "traced" to establish their possible role in the ambush.
Nolascos group had come from a cock derby in nearby Enrile town when they were fired upon in Barangay Pengueruyu here.
The gunmen missed the mayors car and instead hit the back-up vehicle carrying his three civilian security escorts.
Nolasco, 50, escaped unhurt, but his escorts were wounded as they shot it out with the ambushers.
A group of concerned businessmen has offered a P100,000 reward to whoever could give information on the lead gunman whose artists sketch was made public last Friday.