A vehicle exploded injuring several Indonesian police in Surabaya on Monday, a day after Islamist militants killed at least 13 people in suicide attacks on churches in the country's second largest city, police said.
Police have not released the names of the newly arrested suspected terrorists but said they were connected to the perpetrators in the Surabaya attacks, including the family of Dita Oeprianto, who blew themselves up at three churches in the provincial capital on Sunday.
A day before the Islamic holy month of Ramadan, a family of four riding motorcycles loaded with explosives targeted a police station in Surabaya in an attack that injured ten people, including four police officers, according to the Jakarta Post.
The family's eight-year-old girl reportedly survived the explosion and was taken to the hospital, while the rest of the family died in the blast.
At least 23 people have now died, including the attackers, and dozens more injured in the Southeast Asian nation in the past 24 hours.
Shattered glass and chunks of concrete littered the entrance of the church, which was sealed off by heavily armed police.
At Surabaya Centre Pentecostal Church, Futrianto then drove his auto onto the church grounds and detonated explosives.
One of the casualties at Santa Maria Church was Aloysius Bayu Rendra Wardhana, who was killed trying to prevent the suicide bombers from entering the church compound.More news: Ayatollah claims Trump chided Middle East leaders before pulling out of deal
"If he had not stopped the bombers, there would have been more victims (inside the church)", he said.
Earlier, police said his family was among 500 Islamic State sympathizers who had returned from Syria, but the police chief said that was incorrect.
Police in Indonesia say the latest bombings in Surabaya may have been motivated by last week's clashes at a high-security detention center where members of a local militant organization are being held.
In the blast at the Wonocolo low-priced apartments (Rusunawa) in Sidoarjo, AR and two of his younger siblings, FS, 11, and GA, 10, lost their father Anton Ferdiantono, mother Puspitasari and eldest brother HR, 17.
The latest attacks in predominantly Muslim Indonesia came days after police ended a riot and hostage-taking at a detention centre near Jakarta that left five dead. He asked that "everyone find room in their heart for feelings - not of hatred and violence - but of reconciliation and fraternity". The leaders of both groups are now in prison.
"The first wave was linked to Al Qaeda from 2001 and were involved in the Bali attacks", he said.
"We must not be afraid".