The BBC's Anbarasan Ethirajan writes from the capital, Colombo:

Sri Lankans are yet to come to terms with this wave of unprecedented bomb attacks.

It is believed some Muslim youths were radicalised after clashes between the majority Sinhala Buddhists and Muslims last year in the central district of Kandy.

There have been videos on social media showing hardline Islamists and Sinhala hardliners promoting hatred after that violence.

But very few expected such massive attacks a year later. And why were Christians targeted? They are also a minority in Sri Lanka.

The country experienced suicide attacks by Tamil Tiger rebels during the civil war that ended in 2009.

But the ruthlessness with which the latest attacks were carried out show that the country's task this time will be challenging.

It is a different kind of battle. In the meantime, Sri Lankan Muslims are left nervous and afraid.