“Surabaya: Suicide bombers attack Indonesia police headquarters” http://www.bbc.com/news/world-asia-44105279
Police have said the family who carried them out were among hundreds of Indonesians who had returned from Syria, where IS has been fighting government forces. No details were given about the family's alleged involvement in that conflict.
The father has been identified as Dita Oepriarto. Police say he was the head of local branch of Jemaah Ansharut Daulah (JAD), and Indonesian IS-inspired network.
The father then reportedly dropped off his wife, Puji Kuswati, and their two daughters at Diponegoro Indonesian Christian Church, where they blew themselves up. The girls - aged nine and 12 - had bombs strapped to them, as did their mother.
Oepriarto then drove off, launching his own bomb-laden car into the grounds of Surabaya Centre Pentecostal Church, police said.
Thirteen people were killed and more than 40 injured, making it the deadliest attack in Indonesia in more than a decade.
The South East Asian country has long struggled with Islamist militancy. Its worst ever terror attack was in Bali in 2002, when 202 people - mostly foreigners - were killed in an attack on a tourist nightlife district*1.
“Surabaya church attacks: One family responsible, police say” http://www.bbc.com/news/world-asia-44100278
“Surabaya church attacks: Indonesian family of bombers 'had been to Syria'” http://www.bbc.com/news/world-asia-44101070