At least 207 people, including 35 foreigners, have been killed and 400 hurt in a series of explosions at churches and hotels in Sri Lanka.
At least eight blasts were reported. Three churches in Negombo, Batticaloa and Colombo's Kochchikade district were targeted during Easter services, reports BBC.
The Shangri-La, Kingsbury, Cinnamon Grand and a fourth hotel, all in Colombo, were also hit.
A curfew has been imposed from 18:00 to 06:00 local time (12:30-00:30 GMT). Seven arrests have been made.
The government also said there would a temporary block on the use of major social media networks.
No-one has yet claimed responsibility for the attacks but the defence minister said they were probably carried out by one group.
What's the latest from the scene?
St Sebastian's church in Negombo was severely damaged. Images on social media showed its inside, with a shattered ceiling and blood on the pews. Dozens of people are reported to have died there.
There were heavy casualties too at the site of the first blast in St Anthony's, a hugely popular shrine in Kochchikade, a district of Colombo.
Among those killed in Colombo were at least nine foreign nationals, hospital sources told the BBC.
Hospital sources in Batticaloa said at least 27 people had died there.
A hotel official at the Cinnamon Grand, near the prime minister's official residence, said the explosion there had ripped through a restaurant, killing at least one person.
A seventh explosion was later reported at a hotel near the zoo in Dehiwala, southern Colombo, with police sources reporting two deaths. The zoo has been closed.
A bomb goes off as Special Task Force personnel raid a home near Dematagoda in Colombo
An eighth explosion was reported near the Colombo district of Dematagoda. Media say it was suicide bomber and that three people, believed to be security personnel, were killed during a police raid.
Colombo resident Usman Ali told the BBC there were massive queues as he joined people trying to donate blood.
He said: "Everyone had just one intention and that was to help the victims of the blast, no matter what religion or race they may be. Each person was helping another out in filling forms."
Rumours have been reported of more attacks and police have told people to stay inside their houses and remain calm. But there is some element of panic.
There is a heavy military presence in front of all major state buildings. No-one was expecting this, it was a peaceful Sunday morning - everyone was going to Easter services.
Priests at St Anthony's Shrine in Kochchikade
I've spoken to several priests who were in the church and they were really shocked, as were the police officers.
It was a well-planned, co-ordinated attack but I spoke to the security chief who was there and officials believe it's too early to say who is behind it.
After the Tamil Tigers were defeated in 2009, Sri Lanka hasn't really seen this kind of incident.
What have officials said?
Sri Lankan President Maithripala Sirisena has issued a statement calling for people to remain calm and support the authorities in their investigations.
PM Ranil Wickremesinghe is chairing an emergency meeting. He said: "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."
Announcing the curfew, Defence Minister Ruwan Wijewardane said: "We will take all necessary action against any extremist group that is operating in our country."
He also said that "all the culprits" had been identified and would be "taken into custody as soon as possible".
Another minister, Harsha de Silva, described "horrible scenes" at St Anthony's Shrine in Kochchikade, saying he had seen "many body parts strewn all over".
Pope Francis, in his traditional Urbi et Orbi speech at the Vatican, condemned the attacks as "such cruel violence" which had targeted Christians celebrating Easter.
Cardinal Archbishop of Colombo, Malcolm Ranjith, told the BBC: "It's a very difficult and a very sad situation for all of us because we never expected such a thing to happen and especially on Easter Sunday."
UK PM Theresa May tweeted condolences, saying the "acts of violence against churches and hotels in Sri Lanka are truly appalling".
US President Donald Trump tweeted "heartfelt condolences" for the "horrible terrorist attacks".
What's Sri Lanka's recent history?
In the years since the end of Sri Lanka's civil war in 2009, there has been some sporadic violence, with members of the majority Buddhist Sinhala community attacking mosques and Muslim-owned properties. That led to a state of emergency being declared in March 2018.
The civil war ended with the defeat of the Tamil Tigers, who had fought for 26 years for an independent homeland for the minority ethnic Tamils. The war is thought to have killed between 70,000 and 80,000 people.
Religion in Sri Lanka
Theravada Buddhism is Sri Lanka's biggest religion, making up about 70.2% of the population, according to the most recent census.
It is the religion of Sri Lanka's Sinhalese majority. It is given primary place in the country's laws and is singled out in the constitution.
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.