Sri Lanka police investigators said Monday the coordinated Easter Sunday attacks that targeted Christians and luxury hotel guests were the work of seven suicide bombers.

The bombings, Sri Lanka’s deadliest violence since a devastating civil war ended a decade ago on the island nation, killed at least 290 people with more than 500 wounded, police spokesman Ruwan Gunasekara said. Twenty-four arrests have been made but no single group has claimed responsibility for the terror acts, the Sri Lanka Daily Mirror reports.

Defense Minister Ruwan Wijewardena described the blasts as a terrorist attack by “a radical Islamic group.”

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 blast at St Anthony’s Shrine, an historic Catholic Church, was so powerful that it blew out much of the roof, leaving roof tiles, glass and splintered wood littering the floor that was strewn with bodies.

According to the BBC, the international victims include:

At least five British citizens – including two with joint U.S. citizenship

citizens – including two with joint U.S. citizenship Three Danish citizens

citizens One Portuguese citizen and six Indian nationals

citizen and six nationals Two engineers from Turkey , according to Turkish news agency Anadolu

, according to Turkish news agency Anadolu Two Chinese nationals, according to the China Daily

nationals, according to the China Daily Two Australians , Prime Minister Scott Morrison said

, Prime Minister Scott Morrison said One person from the Netherlands

One person from Japan, according to Japanese media citing government sources

Sri Lankan Prime Minister Ranil Wickremesinghe condemned the attacks as “cowardly.’

“I call upon all Sri Lankans during this tragic time to remain united and strong,” he said in a statement Sunday on Twitter. “Please avoid propagating unverified reports and speculation. The government is taking immediate steps to contain this situation.”

Wickremensinghe told reporters that government officials had intelligence about the attacks prior to them occurring, the Washington Post reported.

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

According to 2011 census date, 7.4 percent of Sri Lanka’s 21.4 million population is Christian while 70.2 percent identifies as Buddhist, 12 percent as Hindu and 9.7 percent as Muslim.