Thirteen of the 25 dead victims were the perpetrators, East Java Police Chief Insp. Gen. Machfud Arifin told reporters on Monday.

A family of six, including a 12-year-old and a 9-year-old, were responsible for the deadly bombings of three Surabaya churches on Sunday morning. The church attacks killed 12 people, including Vincencius Evan, 11, and Nathan, 8.

A few hours later, a bomb prematurely went off at the Wonocolo rusnawa (low-cost apartment) located behind Taman Police station in Sidoarjo, East Java.

Three people – the father, the mother and their eldest son – were killed in the Sidoarjo incident, while the two daughters survived. It is believed that the family was plotting to attack the police station.

“This morning, a family of five [attacked the Surabaya Police station]. [They] were carrying a little girl on their motorcycle. This is so heartbreaking,” said Machfud.

The girl survived the attack and has been taken to the nearest hospital.

The police said they were now hunting a fourth family suspected of planning another attack. The family was believed to have recently returned from Syria, large parts of which were once under the control of Islamic State (IS).

The police have not released the identity of the fourth family pending their ongoing investigation.

Dita Oepriarto, the head of the family that carried out the church attacks, and Anton Febrianto, the head of the family in the Sidoarjo incident, were believed to have radicalized members of their families.

Dita was the leader of the East Java branch of Jamaah Ansharud Daulah (JAD), a pro-IS group. (ahw)