JAKARTA - The death toll from the suicide explosions in three churches in Surabaya, the provincial capital of East Java on Friday has risen to 11, including one child, with 41 others wounded, according to a police officer.

Police have discovered three bombs which did not explode in two of the three churches where the bombers blew up themselves during congregations on Sunday morning, provincial police spokesman Senior Commissioner Frans Barung said.

"We have found several bombs which did not explode. But now all of them have been detonated by police," he was quoted by local media as saying.

One of the suicide bombers is a woman who came into the church along with two children. She blew herself up after embracing a security guard at the compound of Gereja Kristen Indonesia on Diponegoro street, according to eyewitness Antonious.

The other perpetrator used a car bomb in the action in Pantekosta church on Arjuna Street, during which two blasts were heard from the car, leaving five other cars and 30 motorcycles ablaze, another eyewitness Wahyudi said.

In Sata Maria church, two bombers suddenly entered the church and blew themselves up, hitting policemen and security guards, eyewitness Yudi said.

President Joko Widodo and National Police Chief General Tito Karnavian will visit the scene, according to the police spokesman.

Indonesian largest Muslim organization Nahdlatul Ulemas and the Asian Muslim Action Network and Wahid Foundation expressed strong condemnation on the brutality against the innocent followers, including children, of the congregation in the three churches.

"We strongly condemned all terrorist acts whatever their motive and backgrounds," the Nahdlatul Ulemas said in a statement.

Sympathy on the victims of the attacks and their relatives was also delivered by the foundation.

All the victims have been rushed to hospital in the city, according to the police spokesman.

The first deadly blast took place in Santa Maria church in Ngagel Madya area at 07:15 am local time, followed by others with interval time of about five minutes.

The perpetrators, disguising themselves as followers of the morning sermons being performed in the churches, exploded the bombs which they were carrying, hitting scores of followers, according to the police.

The police have cordoned off all the scenes for investigation.

The Islamic State group has through its media arm Amaq claimed responsibility for the attacks.