BOGOTA, Colombia — The number of people killed in a bombing in a volatile region in southwest Colombia rose to 20, officials said Sunday.

The attack happened Saturday when an explosive device was detonated on a bus traveling along the Pan-American Highway in the municipality of Cajibio. So far, 15 women and five men are among the victims, according to Octavio Guzmán, governor of the region of Cauca.

He wrote on X that the attack injured 36 others, three of whom are in intensive care. Guzmán noted that five of the injured are minors who are expected to recover.

Colombia’s Institute of Legal Medicine said that specialists including dentists, anthropologists and forensic doctors are identifying the victims.

The bombing is the latest attack in the region, with more than two dozen incidents reported in the past three days in southwestern Colombia. The region is home to illegal armed groups who vie for control of coca leaf cultivation areas and for sea and river access routes to run drug trafficking operations to Central America and Europe.

Gen. Hugo López, commander of Colombia’s Armed Forces, has described the incident as a “terrorist act.” He blamed it on the network of a man known as “Iván Mordisco” — one of Colombia’s most wanted figures — and the Jaime Martínez faction. Both are dissidents of the now-defunct Revolutionary Armed Forces of Colombia that operate in the region.

The U.N. High Commissioner for Human Rights condemned the attacks against the civilian population and called on authorities to investigate the incidents and “guarantee justice for the victims.”

Guzmán declared three days of mourning on Sunday in memory of the victims.