Ambulances and the bomb squad descended on the chaotic scene as the 10 injured people included six civilians and four police men.
But that changed on Sunday as a family of six - including girls aged nine and 12 - staged suicide bombings of three churches during morning services in Surabaya, killing 18 including the bombers. The trio went inside and detonated a bomb.
IS claimed responsibility for the church attacks in a statement carried by its Aamaq news agency.
The police said that both family groups were members of Jemaah Ansharut... Police found the father of the family in a house holding a detonator and shot him, police spokesman Barung Mangera said. Miraculously, the youngest member of the family, an 8-year-old girl, survived and is now being treated as a key witness.
Police say sleeper cells across Indonesia have woken up in the days before Ramadan. The AP reports that, since then, there has been a crackdown on militants in order to prevent terrorism, but authorities have warned that a new threat has been emerging recently. Based on their remains, Karnavian said the mother and daughters were all wearing explosives around their waists.
The IS statement claiming responsibility for the attacks didn't mention anything about families or children taking part and said there were only three attackers.
Police now believe the riot at the Mobile Brigade Detention Center was initiated by a convict acting on the ISIS Central Command's instruction.
"The first wave was linked to Al Qaeda from 2001 and were involved in the Bali attacks", he said.
The government, Indonesian Military (TNI) and the National Police are closely working together to ensure the resort island's security, she added.
Television footage appeared to show a person on a motorcycle driving into the grounds of a church before a bomb was detonated.
That blast killed three people - a couple and their eldest son, 17 - and seriously injured two of their three other children.
Of those, around 400 had returned to Indonesia while 100 are known to have died in battle.
Concerns about sectarian intolerance have been on the rise, with churches targeted in the past.
"In Syria, the Islamic State (in Iraq and Syria) has used children several times in their attacks", Gen Tito told reporters in the press conference.
The victim's mother said the family was "proud to have a martyr who gave his life to save hundreds of people attending Sunday Mass inside the church building".
Almost 90 percent of Indonesia's 260 million people are Muslim, but there are significant numbers of minority Christians, Hindus and Buddhists. His name is Dita Oepriarto.
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