The Jakarta Post
Four of the men involved in the attack on the Riau Police headquarters in Pekanbaru on Wednesday had previously tried to help terror detainees who were rioting at the Mobile Brigade headquarters (Mako Brimob) last week , police said.
"Six men traveled from Sumatra to help the Mako Brimob rioters, but then went back because the situation had been defused," National Police spokesperson Insp. Gen. Setyo Wasisto said on Wednesday. "Two of them were caught in South Sumatra, while the remaining four went to Pekanbaru to carry out the attack, which we successfully stopped."
Setyo confirmed the identity of three of the attackers: Mursalim, 42, Suwardi, 28, and Adi Sufiyan, 26, all of whom were residents of Dumai, Riau. "They were part of the Islamic State of Indonesia (NII) network in Riau, which is part of the ISIS network in Indonesia," he said.
Although NII is separate from the Jamaah Ansharut Daulah (JAD) group that was behind the bombings in Surabaya and Sidoarjo, Setyo said they were all part of the wider pro-Islamic State (IS) network in Indonesia.
"They all pledged allegiance to [IS leader] Abu Bakr al-Baghdadi," he said.