The leader of Paraguay's Armed Peasant Association (ACA) rebel group, Albino Jara, has been killed in a shootout, the authorities say.
Albino Jara was killed in a jungle area near the town of Cuero Fresco, some 480km (300 miles) north of the capital, Asuncion, said a government spokesman.
The ACA is a spin-off from the country's main left-wing rebel group, the Paraguayan People's Army, or EPP.
The government says both groups are criminal gangs.
Another rebel, 18-year-old Liz Rocio Moraes, was killed in the Tuesday night clash.
Three other people were injured but managed to escape.
The EPP rebel group has been active in the impoverished South American nation for more than six years.
The Marxist-inspired organisation is accused of attacking farmers, robbing cattle and kidnapping civilians for ransom.
The Paraguayan government says the ACA, which has been recently formed, is also involved in criminal activities.
Conservative President Horacio Cartes promised to act with "maximum rigour" against the rebels when he took office, in August 2013.
But cattle ranchers in northern Paraguay say they feel unsafe in their own lands.