Around 40 communist guerillas strafed a police convoy in Baggao, a poor farming town in the northeast of the main island of Luzon, sparking a brief firefight, said a regional military spokesman.
The police were responding to a distress call from the builders of a government irrigation project who said the rebels burned their equipment over the weekend, spokesman Lieutenant Colonel Resureccion Mariano told AFP.
Mariano said the rebels attacked the construction site after the contractors refused their extortion attempt.
Police officer Rachie Elpedes from the Baggao police station confirmed the casualties to AFP.
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It was not immediately clear if the rebels suffered casualties, officials said.
The 4,000-strong New People's Army has been waging a 46-year-long guerilla campaign in the countryside and the conflict has claimed 30,000 lives according to official estimates.
The military says the group sustains itself by extorting money from businesses and from candidates during election campaigns.
Repeated efforts by successive governments to arrange peace talks have failed to end one of the world's longest-running communist insurgencies.