Saturday’s bomb attack on a highway in the southwestern Cauca department killed 21 people and injured 56 more.

President Gustavo Petro has deemed it a “terrorist” attack, attributing it to a group of cocaine-smuggling guerrillas.

Police said they arrested Jose Vitonco, the alleged ringleader of a local group of leftist rebels with links to Ivan Mordisco, Colombia’s most-wanted criminal.

A police statement said Vitonco was the “main person responsible” for the devastating attack in Cauca, one of the main areas for the cultivation of coca, which is used in cocaine production – a vital source of income for Colombian guerrillas.

The incident was the biggest single loss of life since the now-defunct Marxist rebel army FARC blew up a Bogota nightclub in 2003, killing 36 people.

It has fuelled fears that violence is on the rise once again, 10 years after FARC agreed to disarm after a half-century of conflict with the state.

Security concerns have dominated campaigning ahead of Colombia’s May 31 presidential election.

The army supported the operation to capture Vitonco in the western city of Palmira, during which police seized a nine-millimeter handgun and seven cell phones from the suspect.

Images released by the authorities show him wearing a bulletproof vest, being escorted by heavily armed police.

Petro said on X that the suspect was an ally of Mordisco, a former FARC commander, who was one of the first rebels to reject the historic 2016 peace deal signed by FARC.

Mordisco now heads the country’s largest dissident rebel group of around 3,200 members.

Petro has often compared him to cocaine baron Pablo Escobar.