Three Peruvian policemen were killed in an attack on patrol vehicles in a drug-trafficking region controlled by a remnant band of Shining Path rebels, the interior ministry said on Thursday.
Authorities are investigating the attack, which occurred late on Wednesday in the jungle region known as the VRAEM, where most of Peru's cocaine is produced, the ministry said.
The Maoist-inspired Shining Path largely ended its armed rebellion in the 1990s on orders from the group's leaders.
But a faction that refused to put down its weapons occasionally ambushes state security forces in the region, where rebels work with drug traffickers.
So far this year, nine police or military officers have been killed in the VRAEM in a sign the Shining Path faction has regrouped after two top leaders were killed in 2013, said Peruvian security analyst Pedro Yaranga.
"This is going to continue," he said.
Peruvian President Pedro Pablo Kuczynski called the latest incident a "cowardly attack" and the interior ministry said it would increase security operations in the region.