Indonesia's elite anti-terror squad was Thursday investigating a suicide bombing attack near a busy Jakarta bus station that killed three policemen, the latest assault in the Muslim-majority country as it faces a surge in militant plots.
Two suicide attackers detonated bombs in a street outside the terminal late Wednesday, sending huge clouds of black smoke into the sky and panicked people fleeing.
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.
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. Security forces have been the main target in recent years of Indonesian militants, who have largely turned their attention away from Westerners.
In a televised address Thursday, President Joko Widodo said he had ordered a thorough probe and was "urging all citizen 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 added.
Authorities have not indicated who might be responsible but Indonesia, the world's most populous Muslim-majority country, has been on high alert after a string of plots in recent times by militants inspired by the Islamic State (IS) group.
After wrapping up a crime scene investigation in the early hours, police handed over the probe to their elite anti-terror squad, which has played a leading role in tracking down and killing some of Indonesia's most wanted militants.
"Anti-terror squad Densus 88 is currently conducting an investigation, we want to know where the bombers came from, which groups they are affiliated to," national police spokesman Setyo Wasisto told AFP.
Wasisto would not be drawn on which group could be behind the attack, but he confirmed 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 the bombs went off 10 to 12 metres (32 to 40 feet) from one another and about five minutes apart.
The terminal is a local hub served by minibuses and buses.
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.
A sustained crackdown weakened the most dangerous networks but the emergence of IS has proved a potent new rallying cry for radicals.
Hundreds of radicals from the Southeast Asian state have flocked to fight with IS, sparking fears that weakened extremist outfits could get a new lease of life.
A gun and suicide attack in the capital Jakarta left four attackers and four civilians dead in January last year, and was the first assault claimed by IS in Southeast Asia.
The country has been hit by a series of low-level attacks since, usually claimed by IS-supporting groups, but most have caused little damage.