A suicide bomber blew himself up outside police headquarters in Indonesia's city of Medan, wounding six people, just a month after an Islamist militant attacked a former security minister.
The explosion happened around 8.45 am local time at a police compound in Medan on Sumatra island.
The motive for Wednesday's attack was not immediately clear but Indonesia, the world's most populous Muslim-majority country, has suffered a resurgence in homegrown militancy in recent years, with some attacks targeting police.
"We suspect this is a suicide bombing with one attacker killed," national police spokesman Dedi Prasetyo told reporters in Jakarta.
"All pieces found at the scene will be tested by a forensic lab to determine the type of bomb," Prasetyo told a news conference."
Indonesia's anti-terrorism unit, Densus 88, was investigating whether it was a "lone wolf" attack or linked to a radical group such as the Islamic State-inspired Jamaah Ansharut Daulah (JAD), which has carried out a series of attacks in the country, he said.
A police officer stands guard near the site of the bombing attack at the local police headquarters. Source: AP
A police source who did not want to be named told AFP that the attack was perpetrated by at least two suicide bombers, but that was not officially confirmed.
Television broadcast images showed smoke and a shower of fragments coming from the parking lot area and people rushing out of buildings around the headquarters after the blast.
The attacker, who was wearing a jacket and had backpack, had his bag checked before entering the car park near an area where people were queuing for clearance letters, North Sumatra police spokesman Tatan Dirsan Atmaja said.
The attack comes a month after a suspected Islamist stabbed and wounded Wiranto, Indonesia's former security minister after he had opened a university building in Pandeglang, west of Jakarta.
Wiranto, who like many Indonesians uses just one name, has since been discharged from hospital after undergoing surgery.
The government scrambled to tighten its anti-terrorism laws after a series of suicide bombings linked to the JAD group killed more than 30 people in the city of Surabaya last year.
Foreseeing an increased threat of attacks from Indonesians who joined Islamic State and have begun returning from the Middle East, police have detained hundreds of suspects since the start of the year.
Members of police forensic team inspect the site. Source: AP
Police spokesman Prasetyo said a man arrested on Tuesday in Bekasi, near Jakarta. He said the man was believed to have fought in Syria and was a suspected JAD member, though he did not draw a direct link to the attack in Medan.
Stanislaus Riyanta, a terrorism expert, said the attack in Medan could be in retaliation for the death of Islamic State leader Abu Bakr al-Baghdadi, who killed himself last month during a US commando raid on his compound in Syria.
