BOGOTÁ — Colombian security forces expanded their manhunt on Monday for those behind a car bombing in Cali, the country's third-largest city, that killed and wounded civilians over the weekend. The explosion struck near a police facility in southwest Colombia, a region long contested by dissident factions of the former FARC guerrilla group and the National Liberation Army.

Local police in Valle del Cauca said they were reviewing security-camera footage and had detained several people for questioning. The Defence Ministry announced it was reinforcing security in urban centres and along major highways in the department.

The attack marked one of the deadliest incidents in Cali in recent years. The mayor called for calm, while the newly inaugurated president vowed to pursue those responsible. Human rights monitors warned that violence by armed groups had intensified in the country's southwest in recent months.

Colombia has struggled to contain a resurgence of guerrilla and cartel activity despite years of peace efforts. Researchers at the Bogotá-based think tank Fundación Ideas para la Paz have documented a sharp rise in attacks on state infrastructure since ceasefire negotiations collapsed.