BUCARAMANGA, Colombia (AP) — One soldier was killed and 12 were injured Wednesday in an attack with explosives on a military unit in western Colombia that the army blamed on the notorious Gulf Clan drug cartel.

The attack occurred early Wednesday in a military facility in the municipality of Turbo, about 480 kilometers (300 miles) northwest of Bogota, Colombia’s capital, the Defense Ministry said in a news release.

The ministry attributed the attack to a faction of the Gulf Clan, considered by authorities to be the country’s largest active drug cartel. The army has been carrying out operations against the group.

The governor of Antioquia, where Turbo is located, offered a reward of almost $12,800 for information leading to the capture the leader of the faction, identified by authorities as Wilder de Jesús Alcaraz, alias “El Indio.”

Colombia’s President Gustavo Petro has been looking to cement a “total peace” plan in the South American country by negotiating peace agreements with all of its armed groups, including leftists guerrillas and trafficking organizations.

The government has ongoing peace negotiations with several different organizations, but has had difficulty holding talks with the Gulf Clan. Last year, the government and the group agreed to a cease-fire, but the authorities halted conversations after accusing the drug cartel of being behind attacks during a mining protest, and the army restarted military operations against it.

In December, six soldiers died and six others were injured in an attack that the government attributed to dissidents from Colombia’s once largest rebel movement, the Revolutionary Armed Forces of Colombia, or FARC.