The death toll in Sri Lanka has soared to 290 after a wave of blasts hit churches and luxury hotels across the country on Sunday.
Police said 24 people had been arrested, but it is not yet known who carried out the attacks.
About 500 people are injured and at least 35 foreigners are among the dead.
The Easter Sunday bombings were the deadliest violence Sri Lanka has witnessed since the end of the country's civil war in 2009.
Late on Sunday, Sri Lankan Prime Minister Ranil Wickremesinghe said security services had been "aware of information" of possible attacks but that the information had not been acted upon.
A local Islamist group known as National Thowheed Jamath is believed to be behind the attack, said cabinet spokeman Rajitha Senaratne.
A curfew is to be imposed from 20:00 (14:30 GMT) until 04:00 on Tuesday, the government said.
How did the attacks unfold?
The first reports of explosions came at about 08:45 local time with six blasts reported within a small space of time.
Three churches in Negombo, Batticaloa and Colombo's Kochchikade district were targeted during Easter services. Blasts also rocked the Shangri-La, Kingsbury and Cinnamon Grand hotels in the country's capital.
All the attacks were carried out by suicide bombers, officials said.
Police then carried out raids on two addresses and there were explosions at both. One was in Dehiwala, southern Colombo, and the other was near the Colombo district of Dematagoda in which three officers were killed.
The air force said an improvised explosive device - a 6ft-long [1.8m] plastic pipe packed with explosives - had been found and disposed of near the airport in the capital, Colombo.
Police have not provided a breakdown of how many were killed and wounded at each location.
What's known about the attackers?
The government has urged people not to speculate about who could be behind the attacks and restricted access to social media in the aftermath of the bombings.
No information has been given on the identity of the 24 people arrested.
However, the BBC's Azzam Ameen in Colombo says the bombers are thought to be part of a "radical extremist Islamist group" according to authorities.
Addressing reports that officials had had prior intelligence of forthcoming attacks, Mr Wickremesinghe said: "We must look into why adequate precautions were not taken. Neither I nor the ministers were kept informed."
A top Sri Lankan official later told the BBC that the government and intelligence services should not be blamed.
Hemasari Fernando - who is also chief-of-staff to President Maithripala Sirisena, a political rival of Mr Wickremesinghe - said information received earlier this month was of only one or two possible attacks, and that he never expected anything of the magnitude of Sunday's bombings.
Who are the victims?
The vast majority of those killed are thought to be Sri Lankan nationals, including scores of Christians who died at Easter church services.
The ministry of foreign affairs says it believes 35 foreign nationals are among the dead.
They include three of the children of Danish billionaire Anders Holch Povlsen, a family spokesman confirmed to the BBC. Mr Povlsen owns the Bestseller clothing chain and holds a majority stake in clothing giant Asos.
Other international victims include:
- At least five British citizens - including two with joint US citizenship
- One Portuguese citizen and six Indian nationals
- Two engineers from Turkey, according to Turkish news agency Anadolu
- Two Chinese nationals, according to the China Daily
- Two Australians, Prime Minister Scott Morrison said
- One person from the Netherlands
- One person from Japan, according to Japanese media citing government sources
What is Sri Lanka's recent history?
Sunday's attacks were the deadliest in Sri Lanka since the end of the country's civil war in 2009.
The war ended with the defeat of the Tamil Tigers, who had fought for 26 years for an independent homeland for the minority ethnic Tamils.
Between 70,000 and 80,000 people are believed to have died in the conflict.
The nation has seen some sporadic violence since. In March 2018 a state of emergency was declared after members of the majority Buddhist Sinhala community attacked mosques and Muslim-owned properties.
Religion in Sri Lanka
Theravada Buddhism is Sri Lanka's biggest religious group, making up about 70.2% of the population, according to the most recent census.
It is the religion of Sri Lanka's Sinhalese majority and is given primary place in the country's laws.
Hindus and Muslims make up 12.6% and 9.7% of the population respectively.
Sri Lanka is also home to about 1.5 million Christians, according to the 2012 census, the vast majority of them Roman Catholic.
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