Authorities in Mexico say gunmen killed five men who were loading sand onto a truck at a riverbank near the resort city of Acapulco, while a shootout in an adjacent state killed one federal police officer and four alleged attackers.
Guerrero state prosecutors say the workers slain Thursday at La Sabana River were between 20 and 25 years of age.
Drug traffickers have extorted companies that transport construction materials as well as other transportation businesses in Acapulco. Authorities say they are investigating whether that was a motive for the killings.
Officials in neighboring Michoacan state say the federal police officer and four gunmen died Wednesday in a clash in the town of Yurecuaro.
State police said Thursday that investigators recovered more than 1,000 spent cartridges at the scene.