The Peruvian military says suspected Shining Path guerrillas killed 19 people in an ambush late Thursday.
The military says 12 soldiers and seven civilians, including a child, were killed in the attack in the southern Huancavelica province.
It says four military vehicles were attacked as they returned to base in the mountainous region.
The Shining Path led a brutal insurgency that started in 1980 and left tens of thousands of people dead. Violence declined sharply after the capture and conviction of rebel leader Abimael Guzman in 1992.
Remnants of the Shining Path continue to carry out small attacks, primarily in remote areas used to produce coca, the raw material in cocaine.