By By By Agence France-Presse
Prime Minister Ranil Wickremesinghe condemned the attacks as "cowardly" and said the government was working to "contain the situation".
Images circulating on social media and local news stations showed extensive damage at one of three churches targeted in the near simultaneous blasts on Sunday morning.
Much of the church roof was blown out in the explosion, with roof tiles and splintered wood littering the floor and pools of blood in between wounded worshippers.
The injured flooded into local hospitals, where officials reported hundreds of wounded were being admitted.
- Police chief warning -
AFP / Sébastien CASTERAN
Blasts hit Colombo, Negombo and Batticaloa
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 first blast was reported at St Anthony's Shrine, a well-known Catholic church in the capital Colombo.
AFP / ISHARA S. KODIKARA
The first explosions were reported at St Anthony's Shrine (pictured) in Colombo and St Sebastian's Church in the town of Negombo just outside the capital
A second deadly explosion was then confirmed 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 town of Batticaloa had been hit, along with three high-end hotels in the capital.
Hospital sources said British, Dutch and American citizens were among the dead, with Britons and Japanese among those injured in the attacks.
- 'Cowardly attacks' -
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."
AFP / ISHARA S. KODIKARA Police said 42 people were killed in Colombo, where three hotels and a church were hit
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.
- 'Horrible scenes' -
"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.
AFP / ISHARA S. KODIKARA
The restaurant area of the luxury Shangri-La Hotel in Colombo was hit
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