Sri Lanka's government has blamed the attacks on three Catholic churches and three luxury hotels on a little-known Islamist group National Tawheed Jamath (NTJ).
Speaking at a press conference, Police Spokesman Ruwan Gunasekara said nine suicide bombers took part in the Easter Sunday bombings.
Out of the nine, eight have been identified. The ninth bomber was confirmed as the wife of one of the suicide bombers, he said.
Sharing more information on the bombers, Minister Wijewardene said most of them are well-educated, and come from middle- or upper-middle-class families.
"They are financially quite independent and their families are quite stable financially," he said.
He added, "We believe that one of the suicide bombers studied in the UK and maybe later on did his post-graduation in Australia, before coming back to settle in Sri Lanka."
Two of the bombers are reportedly brothers and the sons of a wealthy Colombo spice trader. They detonated their explosives at the Shangri-La and the Cinnamon Grand hotels.
The announcement that most of the attackers were "well educated" and "middle class" families is not as surprising as it sounds.
Although poverty and lack of opportunities have steered many youngsters to terrorism, there are also examples of individuals abandoning a relatively comfortable lifestyle for a violent cause.
The late notorious Islamic State executioner Mohammed Emwazi, or "Jihadi John", attended the University of Westminster in London. There have also been cases of British jihadists who have worked for the National Health Service, including doctors, the BBC reported.