COLOMBO, Sri Lanka -- Nine bombings of churches, luxury hotels and other sites on Easter Sunday killed more than 200 people and wounded hundreds more in Sri Lanka's deadliest violence since a devastating civil war in the South Asian island nation ended a decade ago.

Defence Minister Ruwan Wijewardena described the blasts as a terrorist attack by religious extremists, and police said 13 suspects were arrested, though there was no immediate claim of responsibility. Wijewardena said most of the bombings were believed to have been suicide attacks.

The explosions -- mostly in or around Colombo, the capital -- collapsed ceilings and blew out windows, killing worshippers and hotel guests in one scene after another of smoke, soot, blood, broken glass, screams and wailing alarms. Victims were carried out of blood-spattered pews.

"People were being dragged out," said Bhanuka Harischandra, of Colombo, a 24-year-old founder of a tech marketing company who was going to the Shangri-La Hotel for a meeting when it was bombed. "People didn't know what was going on. It was panic mode."

He added: "There was blood everywhere."

Most of those killed were Sri Lankans. But the three bombed hotels and one of the churches, St. Anthony's Shrine, are frequented by foreign tourists, and Sri Lanka's Foreign Ministry said the bodies of at least 27 foreigners from a variety of countries were recovered.

The U.S. said "several" Americans were among the dead, while Britain, China, Japan and Portugal said they, too, lost citizens.

The Sri Lankan government imposed a nationwide curfew from 6 p.m. to 6 a.m. and blocked most social media including Facebook and YouTube, saying it needed to curtail the spread of false information and ease tension in the country of about 21 million people.

Prime Minister Ranil Wickremesinghe said he feared the massacre could trigger instability in Sri Lanka, and he vowed to "vest all necessary powers with the defence forces" to take action against those responsible.

The Archbishop of Colombo, Cardinal Malcolm Ranjith, called on Sri Lanka's government to "mercilessly" punish those responsible "because only animals can behave like that."

Police spokesman Ruwan Gunasekara said at least 207 people were killed and 450 wounded. He said police found a safe house and a van used by the attackers.

The scale of the bloodshed recalled the worst days of Sri Lanka's 26-year civil war, in which the Tamil Tigers, a rebel group from the ethnic Tamil minority, sought independence from the Buddhist-majority country. The Tamils are Hindu, Muslim and Christian.

Sri Lanka, situated off the southern tip of India, is about 70 per cent Buddhist. Scattered incidents of anti-Christian harassment have occurred in recent years, but nothing on the scale of what happened Sunday.

There is also no history of violent Muslim militants in Sri Lanka. However, tensions have been running high more recently between hard-line Buddhist monks and Muslims.

Two Muslim groups in Sri Lanka condemned the church attacks, as did countries around the world, and Pope Francis expressed condolences at the end of his traditional Easter Sunday blessing in Rome.

"I want to express my loving closeness to the Christian community, targeted while they were gathered in prayer, and all the victims of such cruel violence," Francis said.

Six nearly simultaneous blasts took place in the morning at the shrine and the Cinnamon Grand, Shangri-La and Kingsbury hotels in Colombo, as well as at two churches outside Colombo, according to a Sri Lankan military spokesman, Brig. Sumith Atapattu.

A few hours later, two more blasts occurred just outside Colombo, one of them at a guesthouse, where two people were killed, the other near an overpass, Atapattu said.

Also, three police officers were killed during a search at a suspected safe house on the outskirts of Colombo when its occupants apparently detonated explosives to prevent arrest, authorities said.

The Shangri-La's second-floor restaurant was gutted, with the ceiling and windows blown out. Loose wires hung down and tables were overturned in the blackened space. From outside the police cordon, three bodies could be seen covered in white sheets.

Foreign tourists hurriedly used their cellphones to text family and loved ones that they were OK. Visitors from around the world come to Sri Lanka to see elephants, tea plantations, ancient Buddhist monuments and other sights.

"I had a sense that the country was turning the corner, and in particular those in the tourism industry were hopeful for the future," said tourist Peter Kelson, a technology manager from Sydney. "Apart from the tragedy of the immediate victims of the bombings, I worry that these terrible events will set the country back significantly."

Locals who work in Sri Lanka's vital tourism industry were shocked and upset by the bloodshed.

"After so many years, we've started again," said Gamini Francis, 56, a long-time hotel worker. "A lot of people are going to lose their jobs. 100% sure. It's tragic. Crazy people killing innocent people."

Sri Lankan forces defeated the Tamil Tiger rebels in 2009, ending a civil war that took over 100,000 lives, with both sides accused of grave human rights violations.

Harischandra, who witnessed the attack at the Shangri-La Hotel, said there was "a lot of tension" after the bombings, but added: "We've been through these kinds of situations before."

He said Sri Lankans are "an amazing bunch" and noted that his social media feed was flooded with photos of people standing in long lines to give blood.

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Associated Press writers Sheila Norman-Culp and Gregory Katz in London; Sarah DiLorenzo in New York; Jon Gambrell in Dubai, United Arab Emirates; Vladimir Isachenkov in Moscow; Nicole Winfield at the Vatican; Adam Schreck in Bangkok; and Emily Schmall in New Delhi contributed to this report.