SURABAYA, Indonesia - An Indonesian family detonated explosives outside police headquarters in Surabaya, the country's second-largest city, on Monday, a day after members of another family launched coordinated suicide bombings on three city churches that killed at least 14 people and wounding dozens others.

National police chief Tito Karnavian said a girl aged about 8 who was with two of the attackers on a motorcycle survived being thrown by the blast at Surabaya's police headquarters on in the provincial capital of East Java. The attack killed the four perpetrators. Six civilians and four officers were wounded.

The attack came just hours after police said the family that carried out the church bombings included girls aged 9 and 12.

The Islamic State group claimed responsibility for the church bombings through its Aamaq news agency.

Karnavian, however, said earlier police comments that the family had spent time in Syria were incorrect.

He said the church bombers and the police headquarters attackers were friends, as were another family whose homemade bombs exploded in their apartment Sunday night.

'Barbaric'

The use of children in the attacks has been particularly horrifying to people. Indonesia's president Joko "Jokowi" Widodo condemned them as "barbaric" and vowed that authorities would root out and "destroy" extremist militant networks.

Security camera footage of the attack on Surabaya's police headquarters showed at least one explosion after the four attackers rode two motorcycles up to a security checkpoint.

The motorcycles, which moved closely together, pulled up alongside a car and four officers manning opposite sides of the checkpoint. Two men, apparently civilians, were walking into the area just meters from the motorcycles at the moment of the explosion, which a split second later was followed by a second possible blast.

Indonesia's deadliest terrorist attack occurred in 2002, when bombs exploded on the tourist island of Bali, killing 202 people in one night, mostly foreigners. Jemaah Islamiyah, the al-Qaida affiliated network responsible for the Bali attacks, was obliterated by a sustained crackdown on extremists by Indonesia's counterterrorism police with support from the United States and Australia.

Karnavian has said the father of the family that carried out the church bombings was head of the Surabaya cell of Jemaah Anshorut Daulah, an Indonesian militant network affiliated with the IS group that has been implicated in attacks in Indonesia in the past year. All six members of the family were killed.

Ap - Xinhua