There was no immediate claim of responsibility but the government says 13 people had been arrested and police would look into whether the attackers had "overseas links."
Authorities lifted a curfew in the Sri Lanka on Monday, a day after at least 290 people were killed and about 500 wounded by a string of bombings that tore through churches and luxury hotels on Easter Sunday.
The attacks were the worst act of violence to hit the country in the decade since the end of a bloody civil war that killed up to 100,000 people.
For many in Sri Lanka, the apparently coordinated attacks brought back painful memories of life during the long-running conflict, when bomb blasts were a frequent occurrence.
TRT Worl'ds Arabella Munro reports.
The government imposed a nationwide curfew just hours after the attack and curbed social media access to restrict "wrong information" spreading in the country of 21 million people.
There was no immediate claim of responsibility but the government said 13 people had been arrested and investigators would look into whether the attackers had "overseas links."
Sri Lanka says 6 attacks were suicide bombers
A Sri Lankan government forensic crime analyst has told The Associated Press that the six near-simultaneous attacks on three churches and three luxury hotels in and around Colombo were carried out by seven suicide bombers.
Government analyst Ariyananda Welianga says an analysis of the attackers’ body parts collected from the scenes shows that the attacks were suicide bombings.
Welianga says two people were involved in the attack at the Shangri-La hotel. One bomber each attacked the Cinnamon Grand and Kingsbury hotels and St. Anthony’s Shrine in Colombo, St. Sebastian’s church in the city of Negombo and Zion Church in the city of Batticaloa.
Two bombings hours later at a guesthouse and near an overpass on the outskirts of Colombo are still under investigation. Suspects detonated explosives at a safe house near the overpass blast, killing three officers.
Police are examining reports that the intelligence community failed to detect or warn of possible suicide attacks before the violence.
TRT World spoke with journalist Roel Raymond for more.
The powerful blasts – six in quick succession and then two more hours later – injured hundreds.
At least two of them involved suicide bombers, including one who lined up at a hotel breakfast buffet before unleashing carnage.
By Monday morning, the death toll was closing in on 300, with hundreds more wounded.
Police said 35 foreigners were among the dead, including British, Chinese Dutch, Portuguese, Turkish and US citizens.
Turkish Ambassador to Sri Lanka Tunca Ozcuhadar spoke to TRT World about the two Turkish engineers killed in the attacks.
US Secretary of State Mike Pompeo confirmed that "several US citizens" were killed.
Among the churches targeted was the historic St Anthony's Shrine, a Catholic church in Colombo, where the blast blew out much of the roof.
Bodies lay on the ground of the church, covered in patterned scarves and white sheets, some of them stained with blood.
Shattered roof tiles and shards of glass littered the floor, along with chunks of plaster blasted from the walls by the explosion.
TRT World spoke with Hilmy Ahamed, Vice President of the Muslim Council of Sri Lanka about the incident.
Sri Lanka Air Force defused bomb near airport
A Sri Lanka military spokesman said on Monday that an explosive device was also found and defused late Easter Sunday on an access road to the international airport near Colombo.
Air Force Group Captain Gihan Seneviratne said on Monday that authorities found a "homemade" pipe bomb filled with 50 kilograms (110 pounds) of explosives Sunday night in Andiambalama, near the airport.
It's not clear what kind of detonation method or target was planned, but Seneviratne said the bomb was large enough to have caused damage to a 400-metre (400-yard) radius.
'A lot of fear'
Documents seen by AFP show that Sri Lanka's police chief Pujuth Jayasundara issued an intelligence alert to top officers 10 days ago, warning that suicide bombers planned to hit "prominent churches".
"A foreign intelligence agency has reported that the NTJ (National Thowheeth Jama'ath) is planning to carry out suicide attacks targeting prominent churches as well as the Indian high commission in Colombo," the alert said.
The NTJ is a radical group in Sri Lanka that was linked last year to the vandalisation of Buddhist statues.
Prime Minister Ranil Wickremesinghe, speaking late Sunday, acknowledged "information was there" about possible attacks and that an investigation would look into "why adequate precautions were not taken."
Rucki Fernando, a Christian Sri Lankan, told AFP: "We haven't experienced anything like this in the last 10 years."
"There is a lot of fear, not just in the Christian community, but among everyone."
Vineeta Mehra Singh, who was at one of the hotels in Colombo when it was attacked, described the experience to TRT World.
'River of blood'
Sri Lanka's Minister of Economic Reforms, Harsha de Silva, described "horrible scenes" at St Anthony's church.
"I saw many body parts strewn all over," he tweeted, adding that there were "many casualties including foreigners."
Sri Lanka’s Finance Minister Mangala Samaraweera said the multiple bombings are an attempt to cause chaos in the country.
Witness N. A. Sumanapala was near the church when the blast happened.
"I ran inside to help. The priest came out and he was covered in blood," he said.
"It was a river of blood."
A second blast hit St. Sebastian's Church in Negombo, north of the capital during Easter mass.
Gabriel, who declined to give his family name, said his brother was injured in the explosion.
"We are all in shock. We don't want the country to go back to that dark past where we had to live in fear of suicide blasts all the time."
Soon after the first two church blasts, police confirmed that the Zion church in the east-coast town of Batticaloa had been hit, along with three high-end hotels in the capital – the Cinnamon Grand, the Shangri-La and the Kingsbury.
A manager at the Cinnamon Grand, near the prime minister's official residence in Colombo, said a suicide bomber blew himself up at the hotel's restaurant.
"He came up to the top of the queue and set off the blast," he said.
Later in the afternoon, two people died in a strike at a hotel in the south of Colombo, and a suicide bomber killed three police officers as they raided a house in a northern suburb of the city.
Minister @RWijewardene addressing the press just now says action will be taken to stop activity of all extremist groups in the country. Social media temporary banned. 12 hour curfew from 6pm. The Dehiwela n Dematagoda blasts seem to be by those in the ring running from the law.— Harsha de Silva (@HarshadeSilvaMP) April 21, 2019
Prime Minister Wickremesinghe urged people to "hold our unity as Sri Lankans" and pledged to "wipe out this menace once and for all."
The Archbishop of Colombo, Malcolm Ranjith, described the attackers as "animals" and called on authorities to "punish them mercilessly".
Catholic Pope Francis in his Easter address at the Vatican spoke of his "affectionate closeness with the Christian community, attacked while it was at prayer."
Embassies in Colombo warned their citizens to stay inside, and Sri Lankan Airlines told passengers to arrive at the airport four hours ahead of flights because of ramped-up security.
Only around six percent of mainly Buddhist Sri Lanka is Catholic, and the country is a patchwork of different religious and ethnic groups, dominated by Buddhist Sinhalese.
Recent years have seen growing sectarian tensions, including accusations of hate crimes by extremist Buddhist monks against minority Muslims.
There have been no attacks in Sri Lanka linked to foreign groups, but in January, Sri Lankan police seized a haul of explosives and detonators following the arrest of four men from a newly formed radical group.