Two people on a motorbike have carried out a suicide bombing at a police HQ in Surabaya, a day after a wave of deadly blasts in the Indonesian city.

Police officers were injured in the explosion, which occurred at 08:50 local time (01:50 GMT), but the extent of casualties was not immediately clear.

At least 13 people were killed in bomb attacks on three churches on Sunday.

The Islamic State group has said it was behind those attacks.

“We can’t be open up all details yet because we are still identifying victims at the scene and the crime scene is being handled,” East Java police spokesman Frans Barung Mangera told reporters.

It was not yet clear whether the attacks were connected to deadly blasts on Sunday.

In those, a mother and two daughters blew themselves up at a church, while the father and two sons targeted two others.

The bombings are the deadliest in Indonesia in more than a decade, and also left more than 40 people injured.