-- Seven suicide bombers believed to be members of an Islamist extremist group carried out the series of explosions.
-- Police have so far arrested 24 people - mostly members of an Islamist extremist group - in connection with the blasts
Seven suicide bombers believed to be members of an Islamist extremist group carried out a series of devastating blasts that tore through churches and luxury hotels in Sri Lanka on Easter Sunday, killing 290 people in the country's worst terror attack, authorities said on Monday.
A state of emergency was declared from midnight Monday after a crucial meeting of the National Security Council chaired by Lankan President Maithripala Sirisena.
No group has claimed responsibility for Sunday's attacks, but police have so far arrested 24 people - mostly members of an Islamist extremist group - in connection with the blasts that also killed eight Indian nationals.
Police said that nine out of the 24 arrested for involvement in the blasts were ordered to be remanded by the Colombo magistrate's court till May 6.
Government's spokesman Rajitha Senaratne said local Islamist extremist group called the National Tawheed Jamath is suspected of plotting the blasts that struck three churches when the Easter Sunday mass were in progress and three five-star hotels.
"All suicide bombers involved in the blasts are believed to be Sri Lankan nationals," said Senaratne, who is also the Health Minister.
Speaking at a press conference, Senaratne said the government was investigating whether the group had "international support".
"There may be international links to them," he added.
The Government Analyst's Department was quoted as saying by the Sunday Times that the blasts at the Shangri-La, Kingsbury and Cinnamon Grand hotels, and also at St Anthony's Church in Kotahena, St. Sebastian's Church in Katuwapitiya and the Zeon Church in Batticaloa have been identified as suicide bombings.
"A total of seven suicide bombers had carried out these explosions," it said.
Around 290 people were killed in the blasts that left more than 500 others injured, police spokesman Ruwan Gunasekera said.
He said that 24 arrested suspects have been transferred into the custody of the Criminal Investigations Department for further investigations.
The "conditional state of emergency" would target terrorism and would not limit freedom of expression, said a statement from the president's media unit. "These will be limited to counter terrorism regulations. This is being done to allow the police and the three forces to ensure public security."
The government has also declared Tuesday as a national day of mourning.
Lankan President Sirisena has appointed a three-member committee to conduct investigations. The committee will submit its report to him within two weeks.
Health Minister Senaratne said the Chief of National Intelligence had warned the Inspector General of Police regarding the probable attacks before April 11.
"On April 4, international intelligence agencies had warned of these attacks. The IGP was informed on April 9," he said.
He demanded resignation of police chief Pujith Jayasundera in view of the major security lapse.
Senaratne also said that the each victim in the attacks will be paid 1 million Sri Lankan rupees ($5,722), while about 100,000 Sri Lankan rupees ($572) would be given for the costs of the funeral processions.
Lanka's Prime Minister Ranil Wickremesinghe said that an investigation must be launched as to why intelligence reports of the attack was not taken seriously.
Rauff Hakeem, a government minister and the leader of the main Muslim party - Sri Lanka Muslim Congress, said that it was lamentable that no preventive action had been taken despite the inputs.
"They (authorities) have known this (group) for six months, the names have been given, identified but (they) took no action," he added.
Two Sri Lankan Muslim groups - the All Ceylon Jamiyyathul Ulama and the National Shoora Council - have condemned the blasts and demanded that all culprits be brought to book.
Meanwhile, as many as 87 bomb detonators were found on Monday at the Central Colombo bus station in Pettah area. The police initially found 12 bomb detonators scattered on the ground. A further search revealed 75 more, a police statement said.
Also, an explosion took place on Monday when an explosive device in a parked van was being defused by the STF bomb disposal squad near the St Anthony's Church where one of the attacks happened on Sunday. However, there was no casualty.
A safe house where the bombers had lived for nearly three months leading to the attacks was found in the south of Colombo suburb of Panadura.
Sri Lanka Air Force said it found a crude six-foot pipe bomb along a road leading to the departure terminal at the Colombo international airport Sunday night and safely defused it.
The Indian High Commission Monday said Sri Lankan Foreign Ministry confirmed the death of one more Indian, taking the total number of Indian deaths in the blasts to 8 till now.
Sri Lanka on Monday ordered a new night-time curfew following the multiple attacks.
Interpol Secretary-General Jurgen Stock in a Twitter message offered full support to the investigation being carried out by the Lankan authorities.
The blasts shattered a decade of peace in the island nation since the end of the brutal civil war with the LTTE.
The civil war ended with the defeat of the Liberation Tigers of Tamil Eelam, which ran a military campaign for a separate Tamil homeland in the northern and eastern provinces of the island nation for nearly 30 years. The LTTE collapsed in 2009 after the Lankan army killed its supreme leader Velupillai Prabhakaran. The war is thought to have killed between 70,000 and 80,000 people.