A highway bomb attack in a restive region of southwestern Colombia killed 14 people and injured at least 38 on Saturday, the latest spate of violence ahead of next month's presidential election.

Authorities blamed the attack in the Cauca department -- a conflict-ridden, coca-growing region -- on dissidents of the now-disbanded FARC guerrilla army, who have been sowing violence across the country.

"Those who carried out this attack... are terrorists, fascists and drug traffickers," President Gustavo Petro said on X.

"I want our very best soldiers to confront them," he added.

The leftist leader blamed the bombing on Ivan Mordisco, the South American country's most-wanted criminal, whom he has compared to late cocaine kingpin Pablo Escobar.

"As of now, we report 14 people dead and more than 38 injured, including five minors," Cauca Governor Octavio Guzman announced Saturday night on X.

A police source said rescuers were searching for several missing people.

The blast on the Pan-American Highway mangled buses and vans, and several cars had been flipped over by the force of the explosion. A huge crater was carved into the roadway.

Bodies of victims were left on the ground amid the wreckage, covered in sheets.

"It is a terrorist attack against the civilian population," military chief Hugo Lopez told a news conference.

The bomb exploded after assailants stopped traffic by blocking the road with a bus and another vehicle, he said.

"I'm scared," coffee grower Francisco Javier Betancourt, who witnessed the explosion, told AFPTV.

"We're in a country that's finished," he said. "Where else does something like this happen?"

Political violence
The violence came after a bomb attack Friday on a military base in Cali, Colombia's third-largest city, injured two people and set off a string of attacks in the Valle del Cauca and Cauca departments.

According to Lopez, 26 attacks have been recorded in the two departments over the past two days.

Authorities have boosted military and police presence in the areas, Defense Minister Pedro Sanchez said Saturday.

Colombia has a history of armed groups -- which finance their operations through drug trafficking, illegal mining and extortion -- attempting to influence elections through violence.

FARC remnants who rejected a 2016 peace deal with the government have been actively trying to disrupt stalled peace talks with Petro.

Security is one of the central issues of the May 31 presidential election. Political violence was brought into sharp focus last June, when young conservative presidential frontrunner Miguel Uribe Turbay was shot in broad daylight while campaigning in the capital Bogota.

Leftist Senator Ivan Cepeda, an architect of Petro's controversial policy of negotiating with armed groups, is ahead in polls.

He is trailed by right-wing candidates Abelardo de la Espriella and Paloma Valencia, both of whom have pledged to take a hard line against rebel groups.

All three have reported receiving death threats and are campaigning under heavy security.