Indonesia's national police chief says the suicide bombing Monday morning at police headquarters in Surabaya was carried out by members of one family.
National police chief Tito Karnavian said that the father exploded a auto bomb, two sons aged 18 and 16 used a motorcycle for their attack, and the mother was with daughters, aged 12 and 9, for her attack.
Two motorbikes were used in the attack. CCTV footage shows a motorbike approaching the checkpoint and an explosion occurs moments later. All six members of the family died.
Ten people, including four police officers, were injured in the attack.
The footage from the scene, published in social networks, shows how two motorcycles drove up to the police station, then one of them explodes.
Police ordered the temporary closure of all churches in Surabaya yesterday and a large food festival in the city was cancelled.
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Security forces were able to rescue around 50 employees stuck in the building during the attack, he added. But the Islamic State group has also stepped up attacks in recent months, particularly in Kabul.
Monday's attack follows three suicide attacks targeting churches in Surabaya on Sunday that killed at least 13 and injured many others.
According to The Australian, Karnavian said the family had attempted to join ISIS but were arrested by Turkish authorities and were sent back to Indonesia.
JAD is an umbrella organisation on a US State Department "terrorist" list that is estimated to have drawn hundreds of Islamic State sympathisers in Indonesia.
The police identified the father as Dita Oepriarto, saying he was the head of a JAD cell in the area.
The explosions were carefully coordinated and were minutes apart.
The sons - aged 16 and 18 - rode motorcycles into Santa Maria Catholic Church, and detonated explosives they were carrying.
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A split second after the first blast, a possible second blast is seen. He reportedly dropped off his wife, Puji Kuswati, and their two daughters - aged nine and 12 - at Diponegoro Indonesian Christian Church, where they blew themselves up.
The final blast occured at Surabaya Center Pentecostal Church, after the father crashed into the church and detonated a bomb said to have been inside his auto.
Earlier, media reports said a woman with a child and a teenager had just entered one church and was being questioned by security when the bomb exploded.
The police later discovered three bombs at the family's home, the New York Times reported, citing officials in Surabaya.
The Islamic State group has said it was behind those attacks.
Indonesia's president condemned the attacks as "barbaric".
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The visuals of the incident revealed that she was molested by the man with the consent of her mother. The accused came in a Benz auto after the child and her mother arrived at the theatre.
The statement issued Sunday offered condolences to the families of victims and said the United Nations stands by Indonesia's efforts to fight extremism and prevent terrorism.