Nicaraguan police and pro-government paramilitaries moved to reassert control over the city of Masaya by force Tuesday after residents of the opposition bastion declared themselves in rebellion against President Daniel Ortega.
Bursts of gunfire resounded in three neighborhoods, including the main entrance to the city, where government forces have gained control, the head of the Nicaraguan Human Rights Association Alvaro Leiva said.
Three people were killed in this unrest in Masaya, the association said. That brought the death toll in two months of nationwide violence to 186, it added.
As night fell, people in Masaya set up barricades to protect against another government assault. Trucks carrying armed men rumbled through the streets.
Earlier, Leiva said residents were resisting "within the scope of their possibilities" but were under "disproportionate" attack by the security forces.
The pro-Ortega forces used tractors and tow trucks brought in from Managua, 30 kilometers (20 miles) away, to clear barricades from the main road leading to the city.
The auxiliary bishop of Managua, Silvio Baez, appealed to the government to back off.
"Stop the attack on Masaya. Respect the life of the population," he tweeted.
The country's Roman Catholic bishops have attempted to mediate the crisis, which began with anti-government protests in April.
But the latest attempt collapsed on Monday, with the bishops and opposition accusing the government of failing to act on a promise to allow international organizations to investigate the violence.
Masaya, once a bastion of Ortega's Sandinista revolution, has been a focal point of protests aimed at forcing him out of office.
A onetime leftist guerrilla, Ortega led the country from 1979 to 1990 and then returned to the presidency in 2007.