Two people were injured Friday when a bomb went off at a regional branch of the Colombian Attorney General's Office in the southwestern province of Cauca, authorities said.

The device was planted in the rear of the building in Popayan, Cauca's capital, a spokesman for the AG's office told Efe.

A prosecutor and an occupant of another office in the same building suffered slight injuries in the explosion.

The blast and ensuing fire damaged a storage facility holding evidence for current cases as well as 35 nearby homes, according to a preliminary report from the provincial police commander, Col. Ricardo Alarcon.

The bomb contained about 70 kilos (154 pounds) of explosives, he said.

Alarcon said the attack might have been the work of the Revolutionary Armed Forces of Colombia, or FARC, the Andean nation's largest guerrilla group.

The FARC has a strong presence in Cauca. EFE