Sri Lankan authorities have ordered a curfew in the capital, Colombo, for a second day on Monday.
It will be in place from 1430 GMT to 2230 GMT on Tuesday, the government information department said.
So far, the police have arrested 24 people and are carrying out searches across the island.
No group has claimed responsibility for the attacks so far.
The Interpol on Monday said it is ready to offer full support to the Sri Lankan authorities in investigating the attack.
This comes as Prime Minister Ranil Wickremesinghe told reporters that some officials had prior intelligence about the attacks but didn't act on it. "This is a matter we need to look into."
Family of alleged Bondi gunman unaware of 'radical mindset', say Indian police
Israeli forces kill Palestinian teen in West Bank, health ministry says
Trump sues BBC for defamation, seeks up to $10 billion in damages
FBI foils 'terror plot' targeting Los Angeles
Hong Kong court finds tycoon Jimmy Lai guilty in landmark security trial
