WATCH: Sri Lanka Easter attack toll hits 290

COLOMBO, Sri Lanka — At least 290 are now known to have died in a series of bomb blasts that tore through churches and luxury hotels in Sri Lanka, in the worst violence to hit the island since its devastating civil war ended a decade ago.

Eight apparently co-ordinated explosions targeted Easter worshippers and high end hotels popular with international guests.

The horrific death toll, which has risen dramatically overnight, was given on Monday morning by a police spokesman, who said a further 500 people had been wounded.

The news came hours after it was revealed that an improvised bomb discovered at the main airport in Colombo had been defused.

A nationwide curfew imposed shortly after the blasts was lifted early Monday, with AFP journalists reporting a steady stream of people and tuk tuks on the streets of Negombo.

There was still a heavy security presence at the city's St Sebastien's Church, the scene of one of the devastating blasts.

Sri Lanka's small Christian minority -- just six percent of the 21 million-strong population -- has been targeted by violence in the past, but never to such brutal effect.

There was no immediate claim of responsibility, but police said Monday 24 people had been arrested. The government earlier said investigators would to look into whether the attackers had "overseas links".

The powerful blasts -– six in quick succession and then two more hours later -- wounded around 450 people.

At least two of the explosions involved suicide bombers, including one who lined up at a hotel breakfast buffet before unleashing carnage.

The government said the dead included three Indians, three Britons, two from Turkey and one Portuguese national. Two people holding both British and US passports were also among the fatalities.

"Additionally, while nine foreign nationals are reported missing, there are 25 unidentified bodies believed to be of foreigners," the foreign ministry said.

Japan's foreign ministry said one of its nationals was among those who died.

The churches targeted included the historic St Anthony's Shrine in Colombo, where the blast blew out much of the roof.

Bodies lay on the floor of the church, covered in patterned scarves and white sheets, some of them stained with blood.

Shattered roof tiles and shards of glass littered the floor, along with chunks of plaster blasted from the walls by the explosion.

 'A lot of fear' 

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.

Prime Minister Ranil Wickremesinghe acknowledged that "information was there" about possible attacks and that an investigation would look into "why adequate precautions were not taken".

Ethnic and religious violence has plagued Sri Lanka for decades, with a 37-year conflict with Tamil rebels followed by an upswing in recent years in clashes between the Buddhist majority and Muslims.

 'River of blood' 

Sri Lanka's minister of economic reforms Harsha de Silva described "horrible scenes" at St Anthony's church. 

"I saw many body parts strewn all over," he tweeted.

Witness N. A. Sumanapala was near the church when the blast happened.

"I ran inside to help. The priest came out and he was covered in blood," he told AFP. "It was a river of blood."

A second blast hit St Sebastian's Church during Easter Mass.

Gabriel, who declined to give his family name, said his brother was injured in the explosion, adding: "We don't want the country to go back to that dark past where we had to live in fear of suicide blasts all the time."

Soon after the first two church blasts, police confirmed that the Zion church in the east coast town of Batticaloa had been hit, along with three high-end hotels in the capital -- the Cinnamon Grand, the Shangri-La and the Kingsbury.

A manager at the Cinnamon Grand, near the prime minister's official residence in Colombo, said a suicide bomber blew himself up at the hotel's restaurant.

"He came up to the top of the queue and set off the blast," the manager said.

Later in the afternoon, two people died in a strike at a hotel in the south of Colombo, and a suicide bomber killed three police officers as they raided a house in a northern suburb of the city.

 'Animals' 

Wickremesinghe urged people to "hold our unity as Sri Lankans" and pledged to "wipe out this menace once and for all".

The archbishop of Colombo, Malcolm Ranjith, described the attackers as "animals" and called on authorities to "punish them mercilessly".

The attacks drew condemnation from around the world, including from US President Donald Trump and the pope.

Embassies in the capital warned citizens to stay inside, while there were chaotic scenes at Colombo airport as travellers formed huge lines at the only taxi counter that was open.