The explosion exploded near a police station in the city of Santander de Quilichao in the province of Cauca in southwestern Colombia, known as a center for violence and drug smuggling.
Both criminal gangs and members of the Farc guerrilla who refuse to be disarmed are active in the area, writes El Espectador.
Another ten police are reported to have been injured, according to the Reuters news agency.
No special group has been designated as guilty of the attack. Police are expected to hold a press conference on Saturday morning local time.