Eight blasts ripped through high-end hotels and churches holding Easter services that have killed more than 200 people, including 35 foreigners. Prime Minister Ranil Wickremesinghe condemned the attacks as "cowardly" and said the government was working to "contain the situation".
World leaders including France's Emmanuel Macron, Theresa May, Angela Merkel and the EU's Jean-Claude Juncker have joined the chorus of international condemnation.
In a message posted on Twitter, French President Emmanuel Macron said he "firmly condemned the odious acts" perpetrated on Easter Sunday, expressing France's solidarity with the people of Sri Lanka.
We are deeply saddened by the terrorist attacks against churches and hotels in Sri Lanka. We firmly condemn these odious acts. We stand by the people of Sri Lanka and our thoughts go out to the loved ones of the victims on this Easter Sunday. https://t.co/NytqQP9aE7Emmanuel Macron (@EmmanuelMacron) 21 avril 2019
Seven suspects arrested
Sri Lanka’s defense minister said seven suspects were arrested on Sunday. He called it a terror attack by religious extremists.
Authorities have ordered a night curfew and imposed a 'temporary' social media ban.
The first blast was reported at St Anthony's Shrine, a well-known Catholic church in the capital Colombo.
A second deadly explosion was then confirmed at St Sebastian's, a church in the town of Negombo, north of the capital.
Soon after, police confirmed that a third church in the town of Batticaloa, some 200 kilometres to the east of Colombo had been hit, along with three high-end hotels in the capital.
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.
Hospital sources said British, Dutch and American citizens were among the dead, with Britons and Japanese among those injured in the attacks.
Hours after the first explosions, police spokesman Ruwan Gunasekera said a seventh blast hit a hotel in the southern Colombo suburb of Dehiwala and two people were killed.
An eighth blast was reported in a 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.
Intelligence warnings days before
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.
Prime Minister Wickremesinghe called on Twitter for people to avoid speculation.
"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."
Sri Lanka's Minister of Economic Reforms and Public Distribution, Harsha de Silva, said an emergency meeting would be held and rescue operations were underway.
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.
British Prime Minister Theresa May called the attacks "truly appalling".
In her Easter message released just hours before the attacks, May offered her support to Christians around the world who face "huge danger" due to their faith.
"That is why the government has launched a global review into the persecution of Christians."
"We must stand up for the right of everyone, no matter what their religion, to practise their faith in peace," she wrote.
A month after dozens of Muslims were killed in a shooting at two mosques in Christchurch, New Zealand Prime Minister Jacinda Ardern described the attack as "devastating".
"New Zealand condemns all acts of terrorism, and our resolve has only been strengthened by the attack on our soil on the 15th of March. To see an attack in Sri Lanka while people were in churches and at hotels is devastating.
"New Zealand rejects all forms of extremism and stands for freedom of religion and the right to worship safely. Collectively we must find the will and the answers to end such violence."
The Catholic Church in Jerusalem said the blasts were particularly sad as they "came while Christians celebrate Easter".
"We pray for the souls of the victims and ask for speedy recovery of the injured, and ask God to inspire the terrorists to repent of their killing and intimidation," the statement said.