Mexican authorities say they have found the bodies of three police officers and a civilian who were beheaded near the U.S. border.

Officials say four headless corpses were discovered early Wednesday in the northern beach city of Rosarito. Hours later, police found the four severed heads in the nearby town of Tijuana, across from the U.S. city of San Diego.

Authorities say the three municipal policemen went missing in Rosarito late Tuesday. Witnesses say the officers were confronted by a large group of men wearing federal police uniforms.

Mexican towns along the U.S. border have experienced a wave of police killings in recent months, often involving members of rival police forces. Drug-related violence occurs frequently in the area.

Some information for this report was provided by AP and Reuters.