A fresh outbreak of guerrilla violence amid a faltering peace process in Colombia has left more than 80 people dead, including civilians, and displaced thousands in just four days, officials reported Sunday.

As residents fled for their lives, the army deployed some 5,000 troops to the cocaine-growing Catatumbo region at the center of a fast-escalating territorial war.

The National Liberation Army (ELN) armed group, officials said, launched an assault in Catatumbo last Thursday on a rival formation comprised of ex-members of the now-defunct FARC guerrilla force who kept fighting after it disarmed in 2017.

Civilians found themselves caught in the middle, and by Sunday, it was estimated that "more than 80 people have lost their lives," according to governor William Villamizar of the Norte de Santander department.

Terrified residents carrying backpacks and belongings on overladen motorcycles, boats, or crammed onto the backs of open trucks, fled the region over the weekend. 

Hundreds found refuge in the town of Tibu, where several shelters were set up, while others crossed the border to Venezuela — for some a return to a country from where they had fled economic and political upheaval.

Venezuela announced the launch of "a special operation to assist the civilian population displaced from Colombia," — hundreds of families according to the government in Caracas.

House to house

Villamizar said about two dozen people had been injured and some 5,000 displaced in the violence, and described the resulting humanitarian situation as "alarming."

He urged the fighters to create humanitarian corridors by which civilians could safely escape. 

The latest death toll in the restive, mountainous region was 20 more than the number reported by authorities Saturday, which had included seven ex-FARC combatants.

The Ombudsman's Office, a rights watchdog, cited reports of ELN rebels going from "house to house," killing people suspected of ties to the FARC dissidents.

It warned that "peace signatories, social leaders and their families, and even children, face a special risk of being kidnapped or killed" and said many had fled for the mountains.

Army commander Luis Emilio Cardozo said guerrilla fighters took civilians from their homes and "killed them."

He added the army was offering people refuge on military bases, and said food was being delivered to conflict areas.

Classes were suspended in the affected region and schools converted into shelters, authorities said, as Colombian Defense Minister Ivan Velasquez arrived in the city of Cucuta some 60 miles (100 kilometers) from Tibu to oversee a military offensive against the guerrillas.

'War crimes'

The Marxist Revolutionary Armed Forces of Colombia (FARC) — once the largest guerrilla force in the Western Hemisphere — disarmed under a 2016 peace deal reached after more than half a century of war. 

But the pact failed to extinguish the violence involving leftist guerrillas — including the ELN and FARC holdouts — rightwing paramilitaries and drug cartels over resources and trafficking routes in some regions of the country.

The ELN has in recent days also clashed with the Gulf Clan, the largest drug cartel in the world's biggest cocaine producer, leaving at least nine dead in a different part of northern Colombia.

The violence prompted President Gustavo Petro on Friday to call off negotiations initiated with the ELN in his pursuit of "total peace."

With a force of about 5,800 combatants, the ELN is one of the biggest armed groups still active in Colombia. It has taken part in failed peace negotiations with Colombia's last five governments.

While professing to be driven by leftist, nationalist ideology, the ELN is deeply involved in the drug trade and has become one of the region's most powerful organized crime groups.

Talks with the ELN broke down for several months last year after the group launched a deadly attack on a military base.

Following the latest round of fighting, Petro said the ELN "shows no willingness to make peace" in a post on X that also accused the group of committing "war crimes."