Americans, British, Japanese and Dutch citizens were among those killed in the six blasts, which also injured hundreds of people
A series of eight devastating bomb blasts ripped through high-end hotels and churches holding Easter services in Sri Lanka on Sunday, killing nearly 160 people, including dozens of foreigners.
Prime Minister Ranil Wickremesinghe condemned the attacks - the worst act of violence since the end of Sri Lanka's civil war a decade ago - as "cowardly", and said the government was working to "contain the situation".
The powerful blasts - six in quick succession and then two more hours later - wrought devastation, including at the capital's well-known St Anthony's Shrine, a historic Catholic Church.
Hospital sources said British, Dutch and American citizens were among the 158 dead overall, with Britons and Japanese also injured. A Portuguese man also died, the country's LUSA news agency reported.
An AFP photographer at the scene at St Anthony's saw bodies lying on the floor, some draped with scarves and clothes.
Much of the church roof was blown out in the explosion, with roof tiles, glass and splintered wood littering the floor along with pools of blood.
The injured flooded into local hospitals, where officials reported hundreds of wounded were being admitted.
The nature of the blasts was not immediately clear and there were no immediate claims of responsibility.
But 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 Muslim group in Sri Lanka that was linked last year to the vandalisation of Buddhist statues.
The defence ministry ordered a night-time curfew, beginning on Sunday 6:00pm local time (1230 GMT), and a "temporary" social media ban was imposed by the government.
The first blast was reported at St Anthony's, followed by a second deadly explosion at St Sebastian's, a church in the town of Negombo, north of the capital.
"A bomb attack to our church, please come and help if your family members are there," read a post in English on the church's Facebook page.
Soon after, police confirmed that a third church in the east-coast town of Batticaloa had been hit, along with three high-end hotels in the capital.
Later in the afternoon, a hotel in the south of Colombo was struck - killing at least two people and bringing the toll to 158 - while another hit the suburb of Orugodawatta in the north of the capital.
President Maithripala Sirisena said in an address that he was shocked by the explosions and appealed for calm, and the prime minister was expected to speak to the media shortly.
On Twitter, Wickremesinghe wrote: "I strongly condemn the cowardly attacks on our people today.
"I call upon all Sri Lankans during this tragic time to remain united and strong. Please avoid propagating unverified reports and speculation. The government is taking immediate steps to contain this situation."
The hotels targeted in the attack are all popular destinations for tourists, among them the Cinnamon Grand, which is near the prime minister's official residence in Colombo.
An official at the hotel told AFP the blast there had hit the restaurant, and reported at least one person had been killed.
At the Shangri-La hotel, an AFP photographer saw extensive damage on the second floor restaurant, with windows blown out and electrical wires hanging from the ceiling.
"Emergency meeting called in a few minutes. Rescue operations underway," Sri Lanka's Minister of Economic Reforms and Public Distribution, Harsha de Silva, said in a tweet on his verified account.
He said he had been to two of the attacked hotels and was at the scene at St Anthony's Shrine, where he described "horrible scenes".
"I saw many body parts strewn all over," he tweeted, adding that there were "many casualties including foreigners".
"Please stay calm and indoors," he added.
Embassies in Colombo warned their citizens to shelter in place, and Sri Lankan Airlines told customers to arrive at the airport four hours ahead of flights because of ramped-up security in the wake of the attacks.
Only around six percent of mainly Buddhist Sri Lanka is Catholic, but the religion is seen as a unifying force because it includes people from both the Tamil and majority Sinhalese ethnic groups.
There have been no attacks in Sri Lanka linked to foreign Islamist groups, despite local media reports that a 37-year-old Sri Lankan was killed in Syria in 2016 while fighting for the Islamic State group.
In January, Sri Lankan police seized a haul of explosives and detonators stashed near a wildlife sanctuary following the arrest of four men from a newly formed radical Muslim group