Surabaya, Indonesia — Within ten minutes of one another, three churches were hit by a series of explosions killing at least thirteen and wounding over forty. Police have surmised a familial connection between the attackers, who are allegedly members of Jamaah Anshar Daulah, an Islamic extremist group affiliated with the Islamic State in Indonesia.

National Police chief Gen. Tito Karnavian said in a statement that the three churches were the Surabaya Pentecostal Church, Saint Mary Immaculate Catholic Church and the Diponegoro Indonesian Christian Church. The father allegedly dropped off his wife and two daughters at the Diponegoro church, where they conducted one suicide attack. Two sons attacked the Catholic Church via motorcycle and suicide vests; the father activated his suicide vest at the Pentecostal church.

The daughters were 9 and 12 years old; the sons were teenagers. Police have said that the family had been to Syria, though it has not been revealed whether or not they were directly a part of the conflict there. Hundreds of Indonesians have similarly returned from Syria.

Police and private security were put at high alert in churches all across the city. This has been called one of the worst attacks on Christian minorities in the nation in recent history.

An officer leads a sniffer dog at one of the sites of church attacks in Surabaya, East Java, Indonesia, Sunday, May 13, 2018. | AP Photo

Jamaah Anshar Daulah has been linked to ISIS before and several of their attacks in Indonesia. The other major Islamic extremist groups in the country are Jemaah Islamiyah, Mujahidin Indonesia Timur, Jamaah Ansharut Tauhid and Jamaah Ansharusy Syariah. Jemaah Islamiyah (JI) is one of the most prolific and active groups in the area, and they are also active in Singapore, Malaysia and the Philippines.

As ISIS’s power wanes in the Middle East, they have sought to find a foothold in southeast Asia. Countries like Thailand have pockets of extremist presences, especially in the south, but they largely have ulterior motives and are not associated with international organizations like ISIS. ISIS has really found success in expanding their networks throughout Indonesia and the Philippines due to the existing political unrest and large Muslim populations.

ISIS has found wide success in Indonesia. In early 2017, General Gatot Nurmantyo said that,

After observation, we see that in almost every province … there are already IS cells, but they are sleeper cells. These sleeper cells can easily join up with other radical cells … It’s easy to jump from Marawi to Indonesia and we must all beware of sleeper cells being activated in Indonesia.”