Ethiopia announced on Monday it has arrested 15 individuals accused of carrying out assassinations of local government officials.

In a press statement, Oromia Communication Bureau (OCB) said the 15 individuals are suspected of masterminding and carrying out a campaign of assassinations targeting local government officials of Oromia regional state. The suspects are also accused of targeting security forces and civilians.

OCB further said several guns, grenades and other weapons were seized along with the 15 suspects.

The report didn’t mention how many people are believed to have been killed by the suspects and their possible structural affiliation.

However, it said the 15 suspects are believed to have contacts with armed groups operating in some parts of Oromia, an implicit reference to the armed group Oromo Liberation Front (OLF).

OLF is an armed group claiming to fight for the rights of ethnic Oromos who make up about 35 percent of Ethiopia’s estimated 105 million population.

It is estimated there are around 2,800 OLF fighters based mainly in the western and southern parts of Oromia regional state, the principal operating ground of OLF.

OLF rebels have in recent months been accused of conducting deadly assaults on military and civilian targets, including the Sept. 26 killing of four government officials.

OLF was designated as a terrorist group by the Ethiopian parliament in 2011. It was removed from the terror list in July by the Ethiopian government.