Peru's health ministry has sent emergency teams to a remote Amazon region to battle an outbreak of rabies spread by vampire bats.
Four children in the Awajun indigenous tribe died after being bitten by the bloodsucking mammals.
Health workers have given rabies vaccine to more than 500 people who have also been attacked.
Some experts have linked mass vampire bat attacks on people in the Amazon to deforestation.
The rabies outbreak is focused on the community of Urakusa in the north-eastern Peruvian Amazon, close to the border with Ecuador.
The indigenous community appealed for help after being unable to explain the illness that had killed the children.
The health ministry said it had sent three medical teams to treat and vaccinate people who had been bitten.
Most of the affected population had now been vaccinated, it said, although a few had refused treatment.
Vampire bats usually feed on wildlife or livestock, but are sometimes known to turn to humans for food, particularly in areas where their rainforest habitat has been destroyed.
Some local people have suggested this latest outbreak of attacks may be linked to the unusually low temperatures the Peruvian Amazon in recent years.