JEWEL SAMAD/AFP/Getty Images(WASHINGTON) — The Islamic State group claimed responsibility for a wave of coordinated bombings at churches and high-end hotels across Sri Lanka.

The terrorist organization made the claim Tuesday in a statement published in Arabic by its Amaq news agency, saying the attackers were “among the fighters of the Islamic State,” according to a translation by SITE Intelligence Group, a company that tracks extremist groups.

Sri Lankan authorities have not confirmed that report.

At least 310 people were killed and another 500 were injured Sunday when near-simultaneous explosions took place at eight locations across the island nation, which is located off the southern tip of India.

Three explosions erupted at churches holding Easter services while three others happened at hotels, including some commonly used by Western tourists. Most of the explosions were detonated by suicide bombers, according to the Sri Lankan defense ministry.

At least four Americans were among those killed, according to a U.S. official briefed on the investigation. One of the Americans was identified Monday as Dieter Kowalski, 40, of Denver, according to his mother and Pearson, the London-based global education company that employed him.

The Sri Lankan government has blamed the bombings on a little-known domestic Muslim militant group called National Thowfeek Jamaath.

Ruwan Wijewardene, the state minister of defense, told the Sri Lankan parliament Tuesday that authorities have information showing Sunday’s attack was carried out “in retaliation” for last month’s mass shooting at two mosques in New Zealand that killed 50 people.

At least 40 suspects have been arrested around the country in connection to the Easter explosions, Sri Lankan police spokesman Ruwan Gunasekara told ABC News. Twenty-six of them were being questioned by the criminal investigations department Tuesday, while three were being held by the terrorist investigations unit.

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