A group of mothers demand that authorities release their sons who were detained in recent clashes during protests against the government in Managua, Nicaragua, on Friday. (Bienvenido Velasco/Epa-Efe/Rex/Shutterstock)

After a brief pause for dialogue, violence has returned to Nicaragua in recent days, as police and pro-government militias have clashed with protesters and businesses have been looted and burned.

The unrest this past week has intensified a crisis that has gripped Nicaragua since April. Protesters have been demanding the resignation of President Daniel Ortega, a former Marxist guerrilla who is now in his third term in office and holds near total power along with his wife, Vice President Rosario Murillo.

Human rights workers say that some 100 people have been killed since the uprising began. Ortega’s government blames the violence on right-wing agitators.

A march through Managua on Wednesday, led by mothers of those killed during protests, ended when gunmen opened fire on the crowd. Witnesses have accused police and their civilian allies of initiating the violence that left as many as 18 people dead and more than 200 wounded.

Looting, arson and clashes have broken out in different parts of Nicaragua after an initial failed attempt at dialogue between the government, student protesters, business leaders and the Catholic Church.

Every day they’re killing more people,” Gonzalo Carrion, a lawyer with the Nicaraguan Center for Human Rights, said of government forces. “They are causing a wave of terror.”

Before dawn on Saturday morning, an American citizen was killed near the Polytechnic University of Nicaragua, which has been a stronghold of student protest. The man, Sixto Henry Vera, the owner of a sports bar in Managua, had responded to a call that a friend was injured, but his truck got ambushed around 3:00 a.m., according to neighbors. Vera was shot and killed and his vehicle burned, they said.

U.S. ambassador Laura Dogu issued a statement on Twitter offering condolences to the family. “The death of a U.S. citizen is of great concern to our Embassy,” she wrote.

During the first outbreak of violence in mid-April, which occurred amid demonstrations about changes to the social security system, police shot bullets, tear gas and rubber bullets into crowds and detained and roughed up university students in different parts of the country. The unusual surge of protest prompted the government to enter negotiations, mediated by the Catholic Church.

But last week, Cardinal Leopoldo Brenes announced that the talks were suspended indefinitely after a lack of progress. The opposition had called for moving up the date of elections — which are scheduled for 2021 — and prohibiting Ortega from running again. His foreign minister likened the proposal to a coup.

Since then, protesters have erected roadblocks around the country. Students on Monday seized the National University of Engineering in Managua and set fire to Radio Ya, a pro-government station, amid clashes with police.

In an address this week, Murillo, the vice president, denied the existence of government-allied paramilitary groups. She blamed the violence on a “criminal conspiracy that through intimidation, fear, threats and terror, has tried to deliver the country to criminals and organized crime.”

The Inter-American Commission on Human Rights said on May 21, after a preliminary investigation in Nicaragua, that the protests had been characterized “by the excessive use of force by the security forces of the State and armed third persons.”

At that time, the commission said at least 76 people had been killed and 868 injured, the “vast majority in the context of the protests.”

Amnesty International said in a statement this week that the violence during the march led by mothers “demonstrates the systematic ‘shoot-to-kill’ policy of President Ortega’s government.”

On Thursday night, residents of Managua reported hearing gunshots and blasts from homemade mortar tubes and seeing gunmen on the streets of the capital.

“Last night was out of control,” said Mauricio Targa, a businessman who has helped organize protests. “Drive-by shootings. There are muggings. People with ski masks in the back of unregistered cars, armed, pulling people over and robbing them.”

Targa said that makeshift clinics have been set up in people’s homes to treat wounded protesters and that pro-government forces have been taking potshots at these clinics.

“They’re trying to do this to create panic,” he said.

On Thursday, the Organization of American States said in a statement that it “appreciated” the resignation of Roberto Rivas, Nicaragua’s longtime elections chief. Rivas, who had been in his position more than a decade, has been widely criticized for helping Ortega hold on to power. Last year, the United States placed sanctions on Rivas for corruption under the Magnitsky Act, which blocked him from accessing the U.S. financial system.

Ismael Lopez Ocampo in Managua contributed to this report.