Shining Path rebels in Peru have ambushed and killed a police officer and two civilians who were destroying coca plantations, police say.
One police officer was also wounded in the attack in Aucayacu, in the central region of Haunuco, before the rebels escaped into the jungle.
Coca is the raw material for cocaine of which Peru is the world's second-biggest exporter.
It is the first deadly Shining Path attack this year.
Police say they have been combing the area to find the attackers.
The victims were gunned down by sniper fire coming from the thick forest as more than 200 workers were destroying coca plants.
Shock for police
Aucayacu is one of the two remaining rebel holdouts, which explains why more than one 100 armed police officers were there to protect the workers, the BBC's Dan Collyns reports from Lima.
The attack comes as a shock for the police who recently came close to defeating the rebels in this region, he says.
At the height of their power, the Shining Path commanded 10,000 fighters and began a conflict in which nearly 70,000 Peruvians were killed in the 1980s and early '90s.
Now there are just a few hundred rebels split between two key coca-growing areas in Peru's central jungle, who control the lucrative drug-trafficking trade, our correspondent says.
Peru's cocaine production has consistently increased to around 300 tonnes a year while eradication efforts in the world's biggest producer, Colombia, have sharply cut its illegal drug exports.