Sri Lanka’s government says it has information the bombers were reacting to last month’s terrorist attack on mosques in New Zealand

Terrorist group Islamic State claimed responsibility for the coordinated Easter bombings of churches and hotels that killed more than 300 people in Sri Lanka, as investigators worked to identify links with local militants who officials believe helped carry out the attacks.

“The executors of the attack that targeted citizens of coalition states and Christians in Sri Lanka two days ago were Islamic State fighters,” Islamic State said in a brief statement through its affiliated news agency Amaq, which was distributed by security-consulting firm SITE.

Investigators scrambled on Tuesday to arrest suspects and understand the scope of the organization behind the attacks.

Sri Lanka’s government has said it received warnings from security officials in India and the U.S. on April 4 that they had picked up indications attacks were being planned in Sri Lanka. While those warnings didn’t include the name of a group, Sri Lankan security officials linked them to a local radical group, National Thowheeth Jamath, in a circular it distributed to police authorities on April 9.

A senior police official involved with the probes said authorities are casting a wide net to identify accomplices and members of the attackers’ network. Investigators were building on information received before the attacks containing names of suspected extremists planning to target places of religious worship, the official said.