Al-Qaeda has carried out the deadliest attacks in Indonesia, killing more than 200 people on the island of Bali in 2002.
Indonesia's national police chief says the suicide bombing Monday morning at police headquarters in Surabaya was carried out by members of one family.
"This is terrifying", said Taufik Andrie, executive director of an institute that runs programs to help paroled militants reject extremism and rejoin society. "They can't comprehend the decisions involved".
Christians have been targeted before by militants in Indonesia, according to the AP.
The footage of Monday's attack shows the motorcycles, moving closely together, pull up alongside a auto and four officers manning opposite sides of the checkpoint.
Two men, apparently civilians, were walking into the area just meters (yards) from the motorcycles at the moment of the explosion, which a split second later was followed by a second possible blast.
Security footage shows at least one motorcycle was used in Monday's attack. Jemaah Islamiyah, the al-Qaida affiliated network responsible for the Bali attacks, was obliterated by a sustained crackdown on militants by Indonesia's counterterrorism police with USA and Australian support.
An eight-year-old girl, who was reportedly with the family, survived the blast and was being treated in a hospital, said an East Java police spokesman.
"The children probably don't know what's going on or don't understand", he said.
The attacks come days after terrorist Islamist prisoners killed five members of an elite counter-terrorism force during a 36-hour standoff at a high security jail on the outskirts of the capital, Jakarta.
Earlier on Tuesday, police searched the home of the family that bombed Surabaya's police headquarters.
The father of the church suicide bombers was a local leader in extremist network Jamaah Ansharut Daulah (JAD), which supports ISIS.
Before Sunday services, Oepriarto drove his wife Puji Kuswat and the couples two daughters, aged 9 and 12, were the first to carry out the attack. Based on their remains, Karnavian said the mother and daughters were all wearing explosives around their waists.
At Surabaya Centre Pentecostal Church, Futrianto then drove his auto onto the church grounds and detonated explosives.