Indonesian police arrested three people on Friday on suspicion of having links to attacks that killed three police at a Jakarta bus station this week, a spokesman said.
Yusri Yunus, head of public relations at West Java Police, confirmed by text message that the arrests had taken place in the West Java city of Bandung. However, he did not provide details. "We arrested three people in connection with the bombing, in three different locations yesterday afternoon," Yunus told AFP.
On Wednesday, two suicide attackers detonated bombs near a busy Jakarta bus station sending huge clouds of black smoke into the sky. Panicked people were seen fleeing from the scene. The terminal is a local hub served by minibuses and buses.
Reports said the bombers died while five other police officers and five civilians were injured in the assault, which left body parts and glass strewn across the road outside the Kampung Melayu terminal in a working-class district.
The police believe they were targeted in the bombing as they provided security for a parade near the station, which is an area frequented by locals but not foreigners. In recent years, the security forces have been the main target of Indonesian militants, who have largely turned their attention away from Westerners.
President Joko Widodo said on Thursday that he had ordered a thorough probe and was "urging all citizens across the nation to stay calm and remain united". "I convey my deepest condolences to the victims and their families -- especially the police officers who passed away while performing their duty," he said in a televised address.
The police wrapped up a crime scene investigation in the early hours and handed over the probe to their elite anti-terror squad. The squad has played a leading role in tracking down and killing some of Indonesia's most wanted militants.
Setyo Wasisto, national police spokesman earlier said that the bombs were made out of pressure cookers. A pressure cooker bomb was used in an attack in the city of Bandung in February carried out by a militant from an IS-supporting local group called Jamaah Ansharut Daulah (JAD), which has been blamed for a string of recent assaults.
Martinus Sitompul, another police spokesman, told a local TV station that the bombs went off 10 to 12 metres (32 to 40 feet) from one another and about five minutes apart.
Indonesia has long struggled with Islamic militancy and has suffered a series of attacks in the past 15 years, including the 2002 Bali bombings that killed 202 people, mostly foreign tourists.