Peru's Shining Path guerrillas, who vowed last week they would no longer attack government forces, were blamed by authorities for killing a soldier and wounding five others on Monday.
The afternoon attack on a military escort accompanying a field hospital took place in the southeastern district of Santa Rosa in the Ayacucho region, defense minister Luis Alberto Otarola told reporters.
Remnants of the Shining Path guerrilla forces killed the driver of a military vehicle during the attack, officials said.
The Apurimac Ene River Valley (VRAE) region where the attack took place is one of the pockets of territory where the Shining Path still operate. Authorities estimate they now number just several hundred.
They also operate in the Alto Huallaga river region. That branch's leader "Artemio," whose real name is Jose Flores, has repeatedly suggested -- and again just last week -- that the group would stop its attacks and instead seek a "political solution."
Government officials have rejected negotiations with Artemio, saying his capture is imminent.
But the stronger and more aggressive VRAE faction of the guerrillas, which has broken off ties with Artemio's fighters, has avoided talk of a ceasefire.
The rebels were all but eliminated in the 1990s under president Alberto Fujimori, and survivors fled to the mountainous jungle regions on the eastern flanks of the Andes, where they worked as hired guns for drug runners raising coca -- the source plant of cocaine.
Sporadic clashes with the police and army in the VRAE has left about 30 people dead each year since 2008, when authorities launched a crackdown there.
Some 70,000 people were killed between 1980 and 2000 as the Peruvian government crushed the Shining Path and a rival leftist guerrilla group, the Tupac Amaru movement, according to Peru's independent Truth and Reconciliation Commission.