Frans Barung, East Java Police spokesman, informed local media that around 11:30 am (local time) the first explosion was heard coming from the house. A witness then went inside the house to check whether the residents of the house needed help. When the witness smelled gunpowder he became frightened and left the house. Directly after he had left the house a second explosion was heard coming from inside the house. People who had gathered around the house then ran away from the house.

After the second explosion a man was seen exiting the house while carrying a backpack. This man is being searched by the police. According to local media this man, whose name is Anwar (and who originates from Aceh), has been renting the house for two years. While fleeing the scene (by motorcycle) he threatened a local resident (who stood in front of the house) not to reveal his identity. The witness later told police and media that the man was injured (with quite some blood on his face and clothes). The suspect may still have a bomb with him in his backpack.

Mohammad Iqbal, Head of National Police's Public Information Bureau, said that - when fleeing - the suspect also threw two explosives toward police officers that had come to the house to inspect what was going on. He added that the bomb(s) are believed to be low explosives.

It could very well be that the first bomb went off prematurely and was meant to be used for a terrorist attack. This would be very similar to the bomb explosion that occurred in an apartment unit in Sidoarjo (East Java) in early May 2018.

Terrorist attacks in early May in Surabaya (when three churches and local police headquarters were attacked) were performed by cells of the Jamaah Anshar Daulah (JAD) network, one of the local terrorist networks that is affiliated with Islamic State (IS). In these incidents whole families blew themselves up; a new - and eerie - phenomenon in domestic (and international) terrorism.

Aman Abdurrahman is regarded the leader of the JAD network. He is also believed to have masterminded two terrorist attacks in Jakarta in 2016 and 2017. For those attacks the South Jakarta District Court sentenced Abdurrahman to death last month. It could very well be that terrorist cells in Indonesia are looking for revenge after that verdict.

Meanwhile, one day earlier it was reported in local media that Bahrun Naim, one of Indonesia's most notorious militants - who is assumed to have joined the fight alongside the Islamic State in Iraq and Syria (ISIS) -, had been killed in a US drone strike about two months ago. Naim was known for spreading instructional information about the making of bombs. Indonesian authorities can, however, not confirm whether Naim was killed.

Read more: Overview of Radical Islam in Indonesia