Video report by ITV News Asia Correspondent Debi Edward
Sri Lanka’s prime minister has warned the suspects linked to the Easter Sunday bombings remain at large and could still have access to explosives.
Some of the suspects "may go out for a suicide attack”, Prime Minister Ranil Wickremesinghe said in an interview with the Associated Press.
He spoke frankly about the greatest challenge the South Asian island nation has faced since its civil war ended a decade ago.
"This is another experience for us. Not that we are not strangers to terrorism, but this is global terrorism, so we have to ensure that we root this out," Mr Wickremesinghe said.
The death toll has also been revised down from 359 to 253 due to a calculation error said the Sri Lankan health ministry on Thursday evening.
ITV News has obtained CCTV footage which shows the Sri Lanka suicide bomber, who studied in the UK and Australia, walking into a guesthouse moments before he blew himself up, killing two people.
CCTV shows Sri Lanka suicide bomber who studied in UK moments before attack
The CCTV footage, captured by a neighbour, shows a man - who sources have named as Abdul Lathief Jameel Mohamed - wearing white and a backpack.
He disappears from the camera's view as he enters the Tropical Inn guest house in Dehiwala, a suburb of Sri Lanka's capital Colombo, where he went on to detonate his explosives.
The images have been released as the UK Foreign Office has advised against all but essential travel to Sri Lanka.
The attacks were claimed two days later by the Islamic State group, who posted a video of the man Sri Lankan officials say led the attack with seven others.
Police have issued a public appeal for information about three women and two men suspected of involvement in the attacks.
Mr Wickremesinghe also said the father of two of the suspected suicide bombers, Colombo spice dealer Mohammad Yusuf Ibrahim, has been arrested.
He described him as a leading businessman active in politics known as Ibrahim Hajiar, a Sri Lankan term for Muslims who have gone on religious pilgrimages to Mecca.
The prime minister expressed doubt about Mr Ibrahim’s complicity in the attack, saying: "People like that would not have wanted their sons to blow themselves up."
Six near-simultaneous explosions took place shortly before 9am local time in the morning - three at churches and three at luxury hotels.
In Colombo, St Anthony's Shrine and three luxury hotels - the Cinnamon Grand, Shangri-La and Kingsbury, were targeted.
Other blasts were reported at St Sebastian's Church in Negombo, a majority Catholic town north of Colombo, and at Zion Church in the eastern town of Batticaloa.
A few hours later, two more blasts occurred just outside of Colombo, one of them at the guest house, where two people were killed, the other near an overpass.
Three police officers were killed during a search at a suspected safe house on the outskirts of Colombo when its occupants apparently detonated explosives to prevent arrest.
Sri Lankan authorities have blamed a local extremist group, National Towheed Jamaat, but the country has been sharply criticised for an apparent intelligence lapse.
Government leaders have acknowledged some intelligence units were aware of possible attacks weeks before the bombings but the president and prime minister have both said the intelligence was not shared with them.
Mr Wickremesinghe blamed the incident, in part, on a "breakdown of communication".
Sri Lanka's catholic churches have suspended all public services over security fears and Muslims have been urged to avoid gathering for Friday prayers.
Sri Lankan Defence Secretary Hemasiri Fernando has also resigned, taking responsibility for the terror attacks.
A mother and her two children, a brother and sister, a married couple, and a businesswoman from Manchester were the eight British victims killed in the attacks.
Anita Nicholson, her son Alex, 14, and daughter Annabel, 11, who died when one of seven suicide bombers struck as they ate breakfast at the Shangri-La hotel in Colombo.
Londoner Matthew Linsey’s daughter Amelie, 15, and son Daniel, 19, were killed in the same blast on the final day of their holiday.
GP Sally Bradley and her husband Bill Harrop, a retired firefighter, from Manchester, died in the Cinnamon Grand Hotel bombing.
The eighth victim is Lorraine Campbell, 55, from Manchester, who was staying at the Cinnamon Grand Hotel on a business trip.