The calm of Easter Sunday was shattered by gruesome bombings that killed at least 290 people and injured more than 500 innocent people, in Sri Lankan churches and hotels.

Though it's not clear who's behind the eight explosions that forced the country of 21 million people to go on lockdown, they are "certainly acts of terror," said Manisha Gunasekera, high commissioner of Sri Lanka to the UK.

An intelligence memo warning of a possible attack had circulated 10 days earlier, raising questions about whether more preventative measures could have been taken.

"Serious action need to be taken as to why this warning was ignored," Sri Lanka's Minister of Telecommunications, Harin Fernando, tweeted along with a photo of the memo. The document, titled "Information of an alleged plan attack," is dated April 11 and signed by the Deputy Inspector General of Police, Priyalal Dissanayake.

The explosions blew out the tiled roofs of churches and hotel windows, killing worshippers and hotel guests in the process.

Images and footage showed bloodied pews, broken glass, and plumes of smoke.

"You can see pieces of flesh thrown all over the walls and on the sanctuary and even outside of the church," Father Edmond Tillekeratne, social communications director for the Archdiocese of Colombo, told CNN from St. Sebastian's Church, one of the explosion sites.

He estimated that more than a thousand people had come to the church for Easter Sunday "because it is a special day." Many came from villages afar, he said. 

"This is an attack against the whole of Sri Lanka because Sri Lanka is (a) multi-ethnic, multi-religious and multi-cultural country, and the whole country comes together in celebration of Easter Sunday," Gunasekera said.

The violence punctured a decade of relative peace in the country following the end of its civil war in 2009 -- where attacks were common during the 25-year struggle. (Curtesy CNN)

The POSA, Fr. George Pattery SJ, and the entire Jesuits in South Asia condemns the brutal attack on innocent people on Easter Sunday in Sri Lanka and appeal all to pray and work for peace and reconciliation.