In the 8am (local time) incident in Indonesia's second largest city, three suicide bombers simultaneously detonated their explosive devices at the Santa Maria Catholic Church, the Indonesian Christian Church and Pentecost Central Church.
It added that Indonesian police have tightened security in Jakarta, Surabaya and other major cities following the attack.
The official death toll climbed from an initial two killed and may include those who succumbed to injuries in hospital.
Three separate locations were hit by the bombings around 7:30 am (0030 GMT).
A member of the police bomb squad unit examines the site of an explosion outside the Immaculate Santa Maria Catholic Church, in Surabaya, East Java, Indonesia May 13, 2018 in this photo taken by Antara Foto. It was not clear if any other perpetrators were among those killed or injured.
"Three churches were attacked".
"We have confirmed one died at the scene, one died at the hospital, two police officers were injured and there are some civilians injured", Mangera said. Almost 90 percent of Indonesians are Muslim, but the country is also home to sizeable communities of Hindus, Christians, Buddhists, and people who adhere to traditional beliefs. The Islamic State group has claimed responsibility. Resulting in four people were killed, including an alleged terrorist. "Police have arrested a man who was about to attack the fourth Congregational Church, the attack was broken", - quotes the edition the statement of the Deputy mayor of Surabaya, Wisnu Sakti Buana.
Indonesia has carried out a sustained crackdown on militants since bombings by al-Qaida-affiliated radicals in Bali in 2002 killed 202 people.
Hundreds of Indonesians have flocked to fight with IS, sparking fears that extremist outfits could get a new lease on life. The suicide bomber also died.
No Malaysian has been affected by the deadly bombings in Surabaya this morning, a Malaysian embassy spokesman said.
The attacks, which took place during Sunday Mass, has so far killed nine people and left 40 injured.
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