Other images displayed a vehicle engulfed in flames at one location.
National Police Chief Tito Karnavian said the father exploded a auto bomb, two sons ages 16 and 18 used a motorcycle for their attack, and the mother was with her two young daughters for her attack.
They blamed the bombings on the ISIS-inspired group Jemaah Ansharut Daulah (JAD). The U.S. State Department lists JAD as an "umbrella" terrorist organization with hundreds of Islamic State sympathizers in Indonesia.
The Southeast Asian nation, which will begin the holy fasting month Ramadan this week, has been on high alert over attacks by homegrown militants, including some incidents claimed by the Islamic State group. It didn't mention anything about families or children taking part and said there were only three attackers.
Christian devotees attend a Sunday mass, as police stand guard outside, at the Saint Petrus church in Bandung on May 13, 2018.
Photographs from the site showed people lying on the ground outside the church gate.
Tito said that police could not do much against the bomber family soon after they arrived in Indonesia from Syria as the existing terrorism law does not justify legal measurement against them.
The explosions in three churches on the island of Java in Indonesia, six people were killed and another 35 injured. "We would like to offer our condolences and sympathy to the family of the victims and to the Indonesian government", he said in a statement. "All were suicide attacks but the types of bombs are different", he told reporters. They were on a motorcycle and were said to have carried the explosives on their laps.
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On the similar time, the final stated, Sopriyanto's sons drove bikes to Santa Maria Catholic Church, the place they, too, detonated bombs.
In Jakarta, Indonesia's capital, the Indonesian Church Association strongly condemned the attacks and called on people to wait for authorities to investigate.
The first church attack occurred at 7:08 a.m.
In his remarks following the weekly Regina Coeli in St Peter's Square, Pope Francis said he is praying for the victims and their loved ones.
The bombings at three churches in Surabaya - claimed by the Daesh group - were the deadliest in years, as the world's biggest Muslim-majority country grapples with homegrown militancy and rising intolerance towards religious minorities.
"Together we invoke the God of peace (asking him) to cease these violent actions and (to make sure) that in the heart of all there could be a space for feelings not of hatred and violence but of reconciliation and fraternity".
Almost 90 percent of Indonesians are Muslim, but the country is also home to sizeable communities of Hindus, Christians, Buddhists, and people who adhere to traditional beliefs.
"My thoughts are with all those affected by the attacks in France and Indonesia today".
Indonesia has recently become a hot bed for ISIS activity.