(CNN)It's been called "the night of the long knives in the tropics."
In less than a week and just a few months ahead of a crucial election, Nicaraguan police have detained seven high-profile opposition leaders, according to official police statements.
Jose Bernard Pallais Arana was the latest to be arrested. The police said Wednesday that Arana -- the leader of Coalición Nacional party -- was detained for acting "against the independence, sovereignty and auto-determination" of the country.
The same violation is alleged against other detained opposition leaders.
Four leading opposition figures, Félix Maradiaga Blandón, Juan Sebastián Chamorro García, José Adan Aguerri and Violeta Granera were previously arrested on Tuesday. Cristiana Chamorro, another opposition politician, was placed under house arrest on Thursday, and Arturo Cruz was detained on Saturday
Chamorro, Cruz, Maradiaga and Chamorro García had all announced their intention to run against Nicaragua's President Daniel Ortega in the upcoming election.
Ortega, a leftist, former revolutionary whose Sandinista rebels overthrew Nicaraguan strongman Anastasio Somoza in the 1970s, is seeking to win a fourth term on November 7.
Ortega's government has in the past not shied away from cracking down on the opposition. When anti-government protests erupted in the country in 2018, at least 322 people were killed, thousands injured and hundreds detained in just four months. At that time, UN human rights experts accused the government of human rights violations in dealing with protesters.
Ortega said the UN report was "nothing more than an instrument of the policy of death, of the policy of terror, of the policy of lying, of the policy of infamy."
As reports emerged on Tuesday evening of the detention of opposition leaders, former Costa Rican president Laura Chinchilla wrote on Twitter, "this is the night of the long knives in the tropics."
On Wednesday, the US imposed sanctions against senior members of Ortega's regime, including his daughter and the nation's central bank president.
"The United States calls on President Ortega and the Nicaraguan government to immediately release presidential candidates Cristiana Chamorro, Arturo Cruz, Félix Maradiaga, Juan Sebastian Chamorro and other civil society and opposition leaders arrested in the past week, including in last night's crackdown, which sent independent journalists and activists into hiding for fear of reprisals," said US Secretary of State Antony Blinken in a statement announcing the sanctions.
"The region and the international community must stand with the Nicaraguan people in support of their right to freely choose their government and their freedom from repression and human rights abuses," he said.
Accusations against the detained
Maradiaga, the first of the three to be detained on Tuesday, was attending a meeting at the Nicaraguan Attorney General's office when he, his driver and his personal lawyer were held, according to a statement from Maradiaga's office.
Maradiaga "rejected fake accusation against him and demand his immediate liberation," his office added in a statement posted on Twitter hours after his arrest.
The accusations made by the police against Maradiaga, Chamorro García, Adan Aguerri and Arana are similar to the ones faced by Cruz. He was arrested for committing "acts that threaten national sovereignty," according to the Nicaraguan National Police and Public Ministry.
According to a statement posted on Cruz's Twitter account, the former diplomat arrived in Nicaragua on a plane from the United States on Saturday morning and was detained at the Augusto Cesar Sandino Airport in Managua.
Cruz's party, the Citizens for Freedom Alliance, called for his release in a statement. "We demand the prompt release of Arturo Cruz and that his physical integrity and constitutional rights be respected," the opposition party said.
"He is being held incommunicado and nothing is known about his whereabouts," a tweet from Cruz's account read.
Cristiana Chamorro, meanwhile, has been charged with money laundering and the mismanagement of the Violeta Barrios Foundation, a non-profit organization she had chaired, according to the Nicaraguan Public Ministry.
The Violeta Barrios Foundation has been shut down since February due to its violation of the Foreign Agents Regulation Law which was enacted in October 2020. The Prosecutor's Office has asked the judicial authority to impose precautionary measures on Chamorro, including travel restrictions and disqualification from running public office, it said in a statement.
CNN has been unable to reach the legal teams of Aguerri, Chamorro García, Arana and Granera for a response.
The arrests sparked outrage among human rights organizations and foreign leaders.
The US State Department on Friday called on the Nicaraguan government "to immediately release opposition leader Cristiana Chamorro and her two colleagues," calling their detention "on trumped up charges" "an abuse of their rights, and it represents an assault on democratic values as well as a clear attempt to thwart free and fair elections."
State Department spokesperson Ned Price said the "current conditions of repression and exclusion are not consistent with credible elections."
On Tuesday, the Acting Assistant Secretary for US Department of State's Bureau of Western Hemisphere Affairs, Julie Chung, said the detentions called for "an urgent international response."
"The Ortega Regime is responsible for the welfare of detainees. They should be released immediately," Chung tweeted.
Florida Congresswoman Rep. María Elvira Salazar also criticized the move and warned that Ortega's regime "will face the full weight of economic sanctions if free, democratic elections with international observers do not take place."
The Bianca Jagger Human Rights Foundation denounced the detentions, the group's President and Nicaragua-born former actress Bianca Jagger said in a statement on Twitter. She called Ortega "the criminal dictator."
Speaking to CNN Espanol on Thursday, José Miguel Vivanco, the director of Human Rights Watch's Americas division, called on the international community to do more in light of the arrest of Chamorro.
CNN's Gerardo Lemos and Stefano Pozzebon in Bogota, Natalie Gallon in Mexico City and Marlon Sorto, Kiarinna Parisi, Abel Alvarado and Philip Wang in Atlanta contributed reporting. Jenny Hansler, Kylie Atwood, and Nicole Gaouette contributed reporting from Washington, DC.