"The attackers are cruel people. They have damaged state facilities, attacked state apparatus and killed people cruelly," the minister said when he visited the prison on Saturday noon.
Around 17 armed men raided the Cebongan prison in the district of Sleman, Yogyakarta, early on Saturday and killed four inmates and wounded several wardens.
"As a minister of law and human rights I expressed my deep condolences to the victims` families and offered my apology for the failure of my personnel to protect them," he said when inspecting the penitentiary after the incident.
He expressed hope that law enforcers, in this case Yogyakarta police, would soon investigate and uncover the assailants who attacked wardens and cruelly killed four detainees.
The minister said he had heard complete explanations on the chronology of the incident but he would not give details too far.
"We do not want to cause distortion in the (police) efforts to enforce the law. We only ask law enforcers to be serious and transparent. This is not a simple case as this happens for the first time in Indonesia," the minister said.
He said law enforcers must investigate it first and no one may speculate on which group the perpetrators belong to.
"We hope that all sides would hold themselves and would not speculate," he said.
The incident occurred following a clash in Hugo`s Cafe in the district days before that led to the death of a member of Army special force Kopassus.
The chief of the Yogyakarta regional police command, Brigadier General Sabar Rahardjo, said the four killed were "those involved in the clash in Hugo`s Cafe several days ago."