Four social leaders were murdered in Colombia this week, triggering alarm Thursday and raising fears of a possible resurgence of political attacks.

The four victims were identified as Margarita Estupinan, killed in Tumaco, a municipality in the department of Narino bordering Ecuador, which retains one of the highest rates of violence in the country; Ana Maria Cortes, in Caceres, Antioquia; Felicinda Santamaria, in Quibdo, Choco and Luis Barrios Machado, in Palmar de Varela, Atlantico.

The number of murders varies according to the agency that counts them, but Colonel Jose Restrepo, director of a police unit responsible for the protection of social leaders, said that at least 178 of these activists have been murdered in the country since Nov. 2016 when the peace agreement between the government and the Revolutionary Armed Forces of Colombia (FARC) was signed.

The most alarming figure is that of the Ombudsman's Office, according to which 311 social leaders were murdered between Jan. 1, 2016 and Jun. 30, 2018.

The United Nations in Colombia vehemently condemned the incidents on Thursday, saying the latest resurgence of violence in the country impedes progress towards a stable and lasting peace.

This led outgoing Colombian President Juan Manuel Santos to order on Thursday inspectors from the army and the police to investigate the murders and protect other social leaders.

"I want to once again condemn in the strongest terms the murders of the social leaders," the president said during a visit to Tumaco, where he inaugurated a Regional Victim Assistance Center.

He added that the findings of the investigation conducted into the murders will be revealed next Tuesday by the Prosecutor's Office.

President-elect of Colombia, Ivan Duque, condemned during his visit to Washington DC the violence against social and political leaders, and promised that once he officially takes office on Aug. 7, he will bring those committing these crimes to justice and impose "exemplary sanctions."