Unidentified men fired at the FX Tamaraw of candidate Reno Yap at the junction of Sapang Dalaga and Calamba towns at about 5 p.m., police said.
Yap was hit in the back. His uncle, Oscar Miraflor, who was driving the vehicle, rushed him to a nearby hospital. Miraflor and a female passenger were unhurt.
In a statement, Sen. Aquilino Pimentel, PDP-Laban head, condemned the attack which he described as "a glaring illustration of the failure" of the police to carry out "precautionary and pre-emptive measures in areas that are prone to violence."
"If there is one thing that this shooting incident indicates, it is the dismal fact that our law enforcers are sleeping on their job," he said.
Pimentel dared the Misamis Occidental police to go after the ambushers if only to prove that they are not incompetent.
Yap is the third son of Sapang Dalaga Mayor Pacita Yap, who is wanted for criminal cases. His older sibling, Rey, is detained at the National Penitentiary.
Yap is slugging it out with two other candidates for the vice mayoral post.
The Yaps are known political rivals of the Cebedo clan of the adjacent town of Rizal in Zamboanga del Norte. — With Christina Mendez