By Joanna Slater, Amantha Perera, Shibani Mahtani, Washington Post–

Explosions at churches and hotels in Sri Lanka killed 290 people and injured more than 500 Sunday. This is what we know so far:

Government says attack carried out by the local National Thowheed Jama’ath group, with suspected international links.

● Churches were attacked by suicide bombers as worshipers gathered for Easter services.

● Prime minister says elements of government had prior intelligence of attacks.

● At least a dozen of the dead were foreigners, including from India, Japan, the United States and Britain.

● The Sri Lankan air force said they defused an explosive near Colombo’s main airport.

Sri Lanka on Monday accused a local extremist group, the National Thowheed Jama’ath, of being behind a string of Easter bombings against churches and hotels that killed at least 290 people.

Health Minister Rajitha Senaratne said the group, which roughly translates as National Monotheism Organization, perpetrated the attack using suicide bombers against three churches and three hotels, adding that it likely had international links.

On Monday, officials raised the death toll in the Easter Sunday attacks to 290 from 207, underscoring the massive scale of the bloodshed. More than 500 people have been injured.

Attention is now focusing on why and how the government and security forces were unable to foil the coordinated bombings. Two officials provided The Post with a three-page intelligence report issued on April 11, in which a senior police official warned of potential suicide attacks by an Islamic extremist group targeting Catholic churches.

The report also identified the group as the National Thowheed Jama’ath or NTJ and identified several members by name, including its alleged leader, Mohamed Zaharan. The attackers belonged to a “local network,” said Mujibur Rahman, a member of Sri Lanka’s parliament who was briefed on the report, which he said was based on inputs provided by Indian intelligence agencies.

A huge number of the dead were worshipers at St. Sebastian’s Church in Negombo, north of Colombo; officials reported at least 104 dead there. A church in Batticaloa on the island’s eastern shore was also attacked.

The highly coordinated attacks left the island nation reeling, a crushing blow after almost a decade of peace since the end of the civil war.

In that time, tourism in Sri Lanka had been steadily growing, the country transformed by the apparent end of instability, bloodshed and frequent suicide bombings over the 26-year war.

In Colombo, the three high-end hotels attacked included the Shangri-La and the Cinnamon Grand hotel. An official at the Sri Lankan air force said an explosive was defused close to the city’s main airport, the Bandaranaike International Airport, on Sunday night, probably an additional target.

At the Shangri-La Hotel, the blast occurred in a restaurant as guests were having breakfast. Investigators who spoke on condition of anonymity because they were not authorized to speak to the press said that two suspects had checked into a room at the hotel earlier in the morning and gave local addresses to hotel staff.

A curfew has been imposed from 8 p.m. Monday night until 4 a.m. the next morning.

Prime Minister Ranil Wickremesinghe told reporters Sunday that some government officials had prior intelligence about the attacks but didn’t act on it.

“Information was there,” he said at a news conference. “This is a matter we need to look into.”

The security apparatus in Sri Lanka is controlled by the president, Maithripala Sirisena. Relations between him and the prime minister have been at a low point since he tried to oust him from office late last year, launching a political crisis.

Rahman, the member of parliament briefed on the report, is affiliated with the prime minister, and said Wickremesinghe “had the letter in his hand” when he met with lawmakers Sunday, referring to the notice.

“He told us that the Indian intelligence had conveyed threats of possible attacks, two possible dates were mentioned April 4 and 11,” Rahman said. “Part of the problem is since the Oct. 26 coup, the prime minister has not been invited to the security council meetings, so we don’t know what is being discussed,” he added.

Police arrested 13 people in connection with the bombings, and three police officers were killed during a raid at a suspect’s house.

Images of splintered pews and bloodstained floors played across local television screens Sunday as the enormity of the attacks, launched on the holiest day of the Christian calendar, became clear.

From the altar of St. Anthony’s church in Colombo, Father Joy Mariyaratnam looked out at worshipers packed into pews and standing along walls for Easter Sunday.

Nearly halfway through the mass, as the congregation stood to recite prayers, he heard an enormous blast and saw what he described as a fireball.

The explosion was so powerful that it blew off much of church’s roof, sending debris raining down on the people below.

As the smoke cleared, he saw a terrifying scene: scores of wounded and dead, crying out in pain and fear. At first, Mariyaratnam was motionless with panic. “I was thinking, ‘how could such a thing happen in a place of worship?’” he said. “We are still in shock.”

Delicia Fernando, 52, was sitting toward the front of St. Anthony’s church in Colombo with her son and two daughters. Her husband Ravi preferred to stand at the back of the church. Her first impulse after the explosion was to run, but then she and her children turned back to look for Ravi. They found him crushed under debris from the roof, his body pierced with shrapnel.

Sitting in the living room of her parents’ home near the church, she said she had never experienced anything like this violence, not even at the height of the country’s civil war.

Though a majority of the dead were Sri Lankan, at least a dozen were foreigners including from India, Japan, Britain, the United States and Turkey. The unidentified bodies of 25 people believed to be foreigners were at a government mortuary in Colombo.

The dead included “several” Americans, Secretary of State Mike Pompeo said. He blamed “radical terrorists” for the attacks.

Sri Lanka is a predominantly Buddhist nation, but it’s also home to significant Hindu, Muslim and Christian communities. While there has been intermittent conflict between religious groups — including threats to Christians — nothing remotely like Sunday’s attacks had occurred.

Blasts ripped through three churches in Colombo, Negombo and Batticaloa at approximately 8:45 a.m. Sunday as worshipers were gathering for services, police said.

Ruwan Wijewardene, the state defense minister, said the attacks were carried out by suicide bombers. Six of the attacks occurred between 8:45 and 9:30 a.m.

There was a seventh blast at a banquet hall about 2 p.m. and an eighth at the house raided by police around 2:45 p.m.

The deadliest attack was at St. Sebastian’s Church in Negombo, known as “little Rome” for its Catholic presence. Also targeted was St. Anthony’s Shrine, Kochchikade, the largest Catholic congregation in Colombo, and Zion Church in the eastern city of Batticaloa.

Two people at the Shangri-La Hotel described a powerful explosion that made the ground shake just before 9 a.m. Photos showed broken windows and shattered glass on a street next to the hotel.

Sarita Marlou, a guest at the hotel, wrote on Facebook that she felt the impact of the explosion in the hotel’s flagship restaurant all the way up on the 17th floor. She described seeing pools of blood as she evacuated the hotel.

Also targeted were the ground-floor Taprobane restaurant at the Cinnamon Grand Hotel and the luxury Kingsbury Hotel.

Three police officers were killed in a “scuffle” at a home in the Dematagoda area of Colombo, police said. They had gone there to interrogate an individual.

Pompeo condemned the attacks “in the strongest terms.”

“Attacks on innocent people gathering in a place of worship or enjoying a holiday meal are affronts to the universal values and freedoms that we hold dear, and demonstrate yet again the brutal nature of radical terrorists whose sole aim is to threaten peace and security,” he said in a statement.

In an updated travel advisory issued late Sunday, the State Department warned that “terrorist groups continue plotting possible attacks in Sri Lanka,” citing threats to tourist sites, shopping malls, hotels, places of worship and other public areas.

Sri Lankan authorities blocked Facebook and the messaging application WhatsApp in an attempt to halt the spread of false and inflammatory messages. Security was heightened at churches across the country, and the streets of Colombo grew quiet and deserted as the curfew took effect.

Wickremesinghe, the prime minister, condemned “the cowardly attacks on our people today” and urged the country to remain “united and strong.”

The SITE Intelligence Group, which tracks extremist activity online, reported Sunday that Islamic State supporters were portraying the attacks as revenge for strikes on mosques and Muslims.

Yousef A. Al-Othaimeen, the head of the Organization of Islamic Cooperation, “strongly condemned” the “cowardly attacks [on] innocent worshipers and civilians.” The OIC represents 57 predominantly Muslim nations.

People in Sri Lanka expressed a sense of disbelief at the eruption of violence. Biraj Patnaik, South Asia director for the human rights group Amnesty International, said Sri Lanka has witnessed rising hostility toward Christians and Muslims in recent years, including repeated attempted to disrupt prayers at churches. But the scale of Sunday’s attacks, he said, was “shocking and unprecedented.”

The bombings were the worst violence to hit Colombo since 1996, when a blast at the country’s central bank killed nearly 100 people. That attack was carried out by the Liberation Tigers of Tamil Eelam, or Tamil Tigers, which waged a war for a separate Tamil homeland in Sri Lanka’s north for more than 30 years.

Messages of condolence and condemnation on Sunday poured in from around the world.

Pope Francis during his Easter address called the attacks “horrendous” and expressed a “heartfelt closeness to the Christian community, attacked while gathered in prayer, and to all the victims of such a cruel act of violence.”

“I entrust to the Lord all who so tragically died, and I pray for the wounded and all those who suffer because of this traumatic event,” Francis said.

joanna.slater@washpost.com

shibani.mahtani@washpost.com

Mahtani reported from Hong Kong. Rukshana Rizwie in Colombo, Niha Masih in New Delhi, and Chico Harlan in Rome contributed to this report.