The pope addressed "dear people of Indonesia", and especially Christians in Surabaya, saying he was praying for the victims and their loved ones. It didn't mention anything about families or children taking part in the attack, and said there were only three attackers.
A wave of blasts, including a suicide bombing, struck churches in Indonesia yesterday, killing at least nine and wounding dozens of others in the deadliest attack in years to strike the world's biggest Muslim-majority country.
At a news conference later on Sunday, Indonesia's police chief, Tito Karnavian, said the family suspected in the attacks had recently returned from Syria: "Five hundred people were deported from Syria; among them is this family".
Forensic and bomb squad officers searched the area and streets near the bombed churches were blocked by checkpoints and heavily-armed police, Reuters reported.
In the third location, the Indonesian Christian Church, veiled women entered the church's yard where they were stopped by a security guard before an explosion occurred at the same spot, according to the police report.
"All were suicide attacks but the types of bombs are different", he said.
"D then drove the vehicle containing bombs to the Pentecostal Church and blew it up".
According to Open Doors International, which monitors Christian persecution worldwide, persecution is high in Indonesia, and political, cultural and religious forces all contribute to the Christian persecution in this Southeast Asian country.
The bombings were the worst to target churches in Indonesia since a series of attacks on Christmas Eve in 2000 killed 15 people and wounded almost 100.
The Islamic State (IS) group claimed responsibility for that incident although police rejected its involvement. "We would like to offer our condolences and sympathy to the family of the victims and to the Indonesian government", he said in a statement.
Indonesia has had some major successes tackling terrorism inspired by al Qaeda's attacks on the United States in 2001.
National police spokesman Setyo Wasisto announced that police fatally shot four suspected militants and arrested two others early Sunday in West Java towns.
Separately, an internal police report reviewed by Reuters said a suspected bomb exploded in a auto in the parking lot of a Pentacostal church, setting alight dozens of motorbikes.
The Islamic State group was responsible for the attacks, it said via its propaganda agency Amaq. The group is led by Aman Abdurrahman, who is detained at Brimob and who police allowed to speak to the rioters in response to one of their demands.
The Southeast Asian terror network responsible for the Bali attacks was obliterated by a sustained crackdown on militants by Indonesia's counterterrorism police with US and Australian support.
In Jakarta, the Indonesian Church Association condemned the attacks.
Christians, many of whom are from the ethnic Chinese minority, make up about 9 percent of Indonesia's 260 million people.