BOGOTA, April 25 (Xinhua) -- Seven people were killed and more than 20 others injured after a bomb attack struck the Colombian municipality of Cajibio, Cauca department, on Saturday, according to local authorities.

Local media reports said a bomb fell onto a bus on the El Tnel section of the Pan-American Highway linking Cali and Popayan. Online images show severe damage to the bus roof and windows, as well as to the highway.

Multiple drivers testified that armed individuals hijacked a truck and a bus to block the road before the bombing, and sprayed graffiti related to the Revolutionary Armed Forces of Colombia on the vehicles.

Cauca Governor Octavio Guzman condemned the "indiscriminate attack against the civilian population" on social media. He said that public security forces are responding to the attack, urging the Colombian national government to take decisive action to ensure the safety and protect the lives of residents in conflict-affected regions.