An initial probe into deadly suicide bomb attacks in Sri Lanka that killed more than 300 people shows it was “retaliation for Christchurch,” the country’s deputy defence minister said Tuesday.

“The preliminary investigations have revealed that what happened in Sri Lanka (on Sunday) was in retaliation for the attack against Muslims in Christchurch,” state minister of defence Ruwan Wijewardene told parliament.

Fifty people were killed in shooting attacks on two mosques in the New Zealand city of Christchurch on March 15.

Sri Lanka fell silent for three minutes Tuesday on a day of national mourning to honour those killed.

Flags were lowered to half-mast on government buildings, and people bowed their heads and reflected silently on the violence that has caused international outrage.

The silence began at 8:30 am (0300 GMT), the time that the first of six bombs detonated on Sunday morning, unleashing carnage at high-end hotels and churches packed with Easter worshippers.

The first memorial services for the victims, among them dozens of foreigners, were being held Tuesday, hours after the government imposed a state of emergency and said an ISIS group was behind the violence.

The death toll sharply rose to 310, with several people dying of their injuries overnight, a police spokesman said Tuesday. Ten Indians were confirmed to have been killed in the attacks.

Around 500 people were wounded in the blasts, police spokesman Ruwan Gunasekera said in a statement.

The Sri Lankan police have claimed to have arrested 40 people in connection with the suicide blasts.

Earlier on Monday, the Sri Lankan government said that it suspected a local Islamist extremist group called National Thowheeth Jama’ath (NTJ) to be behind the deadly suicide bomb blasts, adding that it was investigating whether the group had “international support.”

Documents seen by AFP show Sri Lanka’s police chief issued a warning on April 11, saying that a “foreign intelligence agency” had reported NTJ was planning attacks on churches and the Indian High Commission.

The blasts targeted St Anthony’s Church in Colombo, St Sebastian’s Church in the western coastal town of Negombo and Zion Church in the eastern town of Batticaloa around 8.45 am (local time) as the Easter Sunday mass were in progress.

Explosions were also reported from three five-star hotels — the Shangri-La, the Cinnamon Grand and the Kingsbury in Colombo.

President Maithripala Sirisena’s office said there was intelligence that “international terror groups” were behind the local perpetrators and that he would seek foreign help to investigate.

(With agency inputs)