Six suicide bombers from one family — including children and teens — rode in on motorcycles and attacked three churches in Indonesia during Sunday Mass, killing at least 13 people, including the family members, and wounding dozens more, police and media reports said.

The family accused of carrying out one of the worst attacks against Indonesia's Christian minority had been in Syria, where ISIS had controlled a large territory in the area until recently, Indonesia’s national police chief Tito Karnavian said. The father, two sons ages 18 and 16, and the mother with two children ages 12 and 9 all took part in the deadly church bombings.

All three attacks targeting Sunday Mass congregations occurred in Surabaya, a city of around 2.8 million people in a country that holds the world’s largest Muslim majority, Reuters reported. At least 13 people, including the family members, were killed and more than 40 people were injured in the blasts.

The first attack that killed four people, including one or more bombers, occurred at the Santa Maria Roman Catholic Church, police told reporters at the scene. Two police officers were among more than 40 wounded, they said. The father of the family accused of carrying out the suicide bombing had detonated a car bomb during his attack.

The incident was followed by a second explosion at the Christian Church of Diponegoro that killed two people. In a third attack, at Pantekosta Church, two more died, police said.

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A witness described the woman with two children, saying she was carrying two bags at the Diponegoro church.

"At first officers blocked them in front of the churchyard, but the woman ignored them and forced her way inside. Suddenly (the bomb) exploded," said a civilian guard named Antonius.

Shattered glass and chunks of concrete littered the entrance of the Santa Maria Church, which was sealed off by heavily armed police. Rescue personnel treated victims on a nearby field while officers inspected wrecked motorcycles in the parking lot that were burned in the explosion.

A street merchant outside the church said she was blown back several yards by the powerful blast. She said she saw two men riding on a motorbike, which Karnivan said the two teenage boys had used in their attack.

"I saw two men riding a motorbike forced their way into the churchyard. One was wearing black pants and one with a backpack," said Samsia, who uses a single name. "Soon after that the explosion happened."

There was no immediate claim of responsibility for the deadly attacks.

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The latest attacks came days after police ended a riot and hostage-taking at a detention center near Jakarta that left six officers and three inmates dead. The Islamic State terrorist group has claimed responsibility.

Indonesia has carried out a sustained crackdown on militants since bombings by Al Qaeda-affiliated radicals in Bali in 2002 killed 202 people.

Churches have been previously targeted in central Jakarta at Christmas in 2000 that killed about 20 people, Reuters reported.

Indonesia has seen a “recent resurgence in homegrown militancy,” the wire service reported.

The Associated Press contributed to this report.