BOGOTA, Dec. 19 (Xinhua) -- Four soldiers were killed and seven others wounded in an explosion at a military base in the city of Aguachica, northeastern Colombia on Thursday, according to the Colombian military.

The attack, carried out by the guerrilla group National Liberation Army (ELN), targeted the base in the Caser department, said a statement from the Second Division of the National Army, which described the attack as a terrorist act involving explosive devices.

Luis Emilio Cardozo Santamaria, commander of the Colombian National Army, said on social media that the ELN's Frente Camilo Torres Restrepo was responsible for the attack. He added that the army forces are conducting joint and coordinated operations to ensure security in the area and carry out relevant deployments.

The ELN, established in 1964, is believed to have thousands of members. Listed as a terrorist organization by the United States and the European Union, it mainly operates in Colombia's Pacific coastal regions and the border between Colombia and Venezuela.