Lt. Col. Harold Argamosa, commander of the Army's 39th Infantry Battalion, said the policemen were responding to a shooting incident when they were ambushed by an undetermined number of communist rebels.
Argamosa said the four policemen died on the spot and another was wounded and rushed to a nearby medical facility.
Killed were Police Officers 1 Rolly Benelayo, Joe Narvasa and PO1 Saro Mangutara, members of the Bansalan Police Station; and Police Officer 3 Hayden May Raden of the Digos City police's forensics unit.
The injured policeman was identified as Police Officer 3 Allen Amado.
Armagosa said pursuit operations are ongoing against the Communist members.
He also added that military and police units in Davao del Sur have been placed on heightened alert status following the attack.