A second family have blown themselves up at a police headquarters in Indonesia's second city Surabaya on Monday, a day after another family killed at least 13 people in coordinated attacks against three churches in the same city.
A girl thought to be about eight years old survived Monday's attack after being thrown off a motorcycle driven by two of the attackers, national police chief Tito Karnavian said. The four perpetrators were killed in the attack, which wounded four officers and six civilians.
Ambulances and the bomb squad descended on the chaotic scene. CCTV images showed a child stumbling around the mangled wreckage of a motorbike at the security gate at the headquarters in the heart of the city.
There was no immediate claim of responsibility after the latest suicide bombing but ISIS claimed responsibility for the earlier church bombings in a statement carried by its Amaq news agency. Police chief Karnavian said that the two families were friends. The family that carried the earlier attacks included girls aged nine and 12.
President Joko Widodo branded the attacks in Surabaya the "act of cowards", and pledged to push through a new anti-terrorism bill to combat Islamist militant networks. "There will be no compromise in taking action on the ground to stop terrorism," he told reporters.
The attacks have raised fears that previously subdued extremist networks in Indonesia have been reinvigorated by the return of some of the estimated 1,100 Indonesians who joined ISIS in Syria and Iraq. Experts have warned that returning militants could pose a threat to the world's most populous Muslim-majority country. Karnavian, however, said earlier police comments that the church attack family had travelled to Syria were incorrect.
A third family has also been connected to the attackers, after a homemade bomb exploded in their apartment Sunday evening. Three members of that family were killed in the explosion in Sidoarjo, a town near Surabaya, police said. Three children from the family survived and were taken to hospital.
Indonesia has experienced a resurgence of terrorist attacks in recent years, with bombs striking targets ranging from churches and police stations to Starbucks cafes. The country's largest attack occurred in 2002 on the tourist island of Bali, where bombs exploded at nightclubs, killing 202 people in a night.
During an ensuing crackdown against Jemaah Islamiyah, the al-Qaida affiliated network responsible for the Bali attacks, hundreds of militants were arrested and the groups leaders killed in police raids. With US and Australian support, Indonesian counter-terrorism police were able to wipe out the network.
Police said the father of the family that carried out the church bombings led the Surabaya cell of Jemaah Anshorut Daulah (JAD), an ISIS-affiliated group. JAD is an umbrella organization on a US State Department terrorist list that is believed to have attracted hundreds Indonesian ISIS sympathizers and has been implicated in attacks in Indonesia in the past year. Karnavian said the JAD cell may have been answering a call from ISIS in Syria to "cells throughout the world to mobilize."
The police chief said the father drove a bomb-laden car into the city's Pentecostal church. The mother, with her two daughters, attacked the Christian Church of Diponegoro, he said. Based on their remains, Karnavian said the mother and daughters were all wearing explosives around their waists.
The sons aged 16 and 18 rode a motorcycle onto the grounds of the Santa Maria Church and detonated their explosives there, he said.
The church attacks occurred within minutes of each other, according to Surabaya police spokesman Frans Barung Mangera. All six members of the family died.
The ISIS statement claiming the attacks didn't mention the involvement of women or children, though the group has used women as suicide bombings infrequently in the past. Security experts said it was the first time in Indonesia that a child had been used by militants on a suicide mission. The group also claimed responsibility for a hostage-taking ordeal last week by imprisoned Islamic militants at a detention center near Jakarta in which six officers were killed.
In all, 25 people have died since Sunday in attacks, including 13 suspected militants, police said. But with more than 40 injured civilians in hospital, the death toll could climb higher.