Gunmen have kidnapped the sole police officer in a northern Mexican town, a 28-year-old woman working alone after her colleagues resigned or were killed.

A letter was purportedly signed by the La Familia drug cartel announcing a one-month truce circulated Sunday in the western state of Michoacan, Mexico.

The Mexican government’s security strategy has succeeded in weakening Mexico’s drug cartels, including the Pacific cartel, whose members accounted for 24 percent of the drug arrests made in the country this year, Mexico's Security Cabinet said.