The police arrested 24 people in connection with the suicide bombers. This is the worst act of violence the South Asian island has experienced since the end of its bloody civil war 10 years ago.
A ninth improvised explosive device (IED) was compensated on Sunday evening near the capital's international airport, Bandaranaike, according to an Air Force spokesman. The blasts seem to have focused on tourism hotspots and churches for maximum global attention.
Foreigners are among the dead, including five British citizens, two of whom had dual US citizenship, three Indians, two Australians, two Chinese cousins, one Dutch person, two Turkish citizens, and one Portuguese.
No group has blamed the attacks, but Sri Lankan Defense Minister Ruwan Wijewardene said the "terrorist attack" is being carried out from "torture" to "religious extremism".
Sunday night, a leaked memo revealed that the police had been warned of a possible attack by the Nations Thawahid Jaman (NTJ), an Islamist group led by Mohomad Saharan. It is not clear if the information was related to Sunday's bombings.
The Prime Minister of Sri Lanka said he and other ministers were not warned. Sajith Premadasa, Minister of Housing and Cultural Affairs, said the officers had acted "carelessly and incompetently".
Analysts, however, have warned against rushing to conclusions. Dhruva Jaishankar, a fellow in foreign policy studies at Brookings India, said the NTJ was a little-known group that had previously defaced Buddhist statues and unlikely the ability or sophistication to carry out an attack like Sunday without support.
While there is a transnational Islamist presence in countries like Pakistan, Malaysia and the Philippines, Jaishankar said that little is known about Islamic radicalism in Sri Lanka and that it is "premature" to speculate about which organizations may be involved were .
Christianity is a minority religion in Sri Lanka and accounts for less than 10% of the total population of 21.4 million people. According to census data, 70.2% of Sri Lankans are Buddhists, 12% Hindus, 9.7% Muslim and 7.4% Christian.
It is estimated that 82% of Christians in Sri Lanka are Roman Catholics.
A social media blackout was enforced as authorities sought to stem violence and determine who carried out the attacks and why.
How it unfolded
The first wave of attack during the Easter Sunday services.
More than 1,000 people arrived at one of the explosion sites, the Church of St. Sebastian, says Father Edmond Tillekeratne, director of social communications for the Archdiocese of Colombo.
When the Easter church services began in churches in the cities of Colombo, Negombo and Batticaloa, the bombers detonated their devices. The bombs blew up the tiled roofs of the churches, killing the worshipers. Pictures showed bloody benches, broken glass and smoke.
"There are pieces of meat everywhere on the walls and the sanctuary and even outside the church," Tillekeratne said.
Further explosions have taken place in three luxury hotels in the capital, Colombo: the Shangri La, the Cinnamon Grand and Kingsbury, which is popular with foreign tourists and the country's business community. At Shangri-La, shortly after 9am local time, the bomb detonated at Table One Café as vacationers and guests had breakfast.
Jaishankar, who visited the three hotels, said there was "very little security" at one of the venues.
Another explosion shook a hotel in front of the Dehiwala Zoo in Dehiwala-Mount Lavinia. The last explosion hit a private house in the Mahawila Gardens in Dematagoda during a raid in connection with the attacks. Three policemen were killed.
On Monday morning, the beach district of the city, where several bombs were knocked down, was guarded by soldiers carrying AK47s and bomb sniffing dogs in front of closed hotel gates where guests were checked in.
Rising of ISIS in Asia
The Sri Lankan Prime Minister Premadasa described Sunday's attacks as a "brand new kind of terrorism".
"We have had no separatist movements in the last 10 years and that was a shock to us all of us," he said.
The civil war between the Tamil Tigers separatists and the Sri Lankan government ended in 2009 after claiming between 70,000 and 80,000 lives. The confrontation with this conflict has prepared the government for dealing with terrorism.
"During the 30-year terrorist war, there were indiscriminate attacks on all the institutions that did not spare them (the Tamil Tigers) separatist state on their way to conflict, but we defeated terrorism," he added.
The goals of the attacks – churches filled with believers on Easter Sunday, and three five-star hotels dealing with foreigners – have increased in recent years past years in Asia and beyond.
In January 2019, ISIS assumed responsibility for an attack on at least 20 killed in a church in the Philippines. The attack also took place on a Sunday when worshipers were gathered for mass.
In May 2018, ISIS took responsibility for attacks on three churches in Indonesia, killing at least 12 people and injuring dozens more. And on Palm Sunday 2017, ISIS killed at least 49 people gathered in two Egyptian churches for Mass.
Jaishankar said Sri Lanka had become complacent since the end of his civil war. "This could end up as a wake-up call," he added.
CNN's Tara John and CNN National Safety Analyst Peter Bergen also contributed to this report. Journalist Sandun Arosha F & do reported from Colombo, Sri Lanka.