Nicaraguan government security forces have launched raids to clear protesters’ barricades in opposition hotspots, leaving at least 10 dead.
Human rights organisations say at least six civilians were killed along with four members of the security forces.
The operation targeted the city of Masaya and several smaller communities and neighbourhoods in the area.
The EU, Colombia, Chile and Ecuador criticised the government’s actions.
Álvaro Leiva, the head of Nicaraguan Association For Human Rights (ANPDH), said at least 22 vehicles carrying government security forces had arrived in the area.
Labelled “Operation Clean-up” by the government, it concentrated on the city of Masaya, nearby Niquinohomo and Catarina villages and the neighbourhood of Monimbo.
Mr Leiva warned people in the city of Masaya to stay indoors, saying “there are sharpshooters stationed at different places around the city”.
Earlier he said police had not been allowing the wounded to reach hospitals in the area.
One resident in Masaya told the French news agency AFP: “We are being attacked by the national police and paramilitaries armed with AK-47s.”
The latest government action came a day after dozens of students in the capital Managua were besieged by pro-government forces for hours in a parish church next to the National Autonomous University of Managua (UNAN) before finally being allowed to leave after the intervention of Catholic Bishops.
Two students died in the action and many said they felt the security forces had been shooting to kill.
The UNAN was the last bastion of student resistance in the capital after months of nationwide anti-government protests in which over 300 people have been killed.