Jakarta: Suicide bombers struck three churches in Indonesia's Surabaya city killing at least nine people, police said on Sunday.

The first explosion was at a Catholic church at about 7.30am on Sunday morning.

It's understood that one suicide bomber and one church goer were killed in the first explosion.  At least one woman was killed in the second explosion. There have now been 40 people injured and admitted to hospital.

All other masses in Surabaya scheduled for Sunday have been cancelled and Indonesian police are now searching other churches and working to head off any further attack.

Approximately 30 minutes later, a second blast occurred at a Protestant church on Diponegoro street and the third blast occurred soon afterwards at a Pentecostal church in the city.