This is a curious series of attacks. First of all, multiple targets where the bombs went off around the same time and one sometime afterwards. Then there is the absence of anyone or any group claiming responsibility. Christians make up 7.5% of the population, which is very religious. So is this the work of one person planting the bombs?

I see the BBC report refers to suicide bombers:https://www.bbc.co.uk/news/world-asia-48001720

For background:https://en.wikipedia.org/wiki/Sri_Lanka