Colombo: Sri Lankan police have arrested 13 men in connection with bomb blasts on churches and hotels that killed more than 200 people, officials said Monday.

Authorities have not made public details on those held after Sunday's attacks. But a police source told AFP the 13 were detained at two locations in and around Colombo.

The source said the 13 men are from the same radical group. At least two of the eight attacks were carried out by suicide bombers, according to police and other sources, and three police were killed when another suicide bomber detonated explosives during a raid on a house where suspects were.

A string of eight powerful explosions, including suicide attacks, struck churches and luxury hotels frequented by foreigners in Sri Lanka on Easter Sunday, killing 215 people, including three Indians, and shattering a decade of peace in the island nation since the end of the brutal civil war with the LTTE.

The blasts - one of the deadliest attacks in the country's history - 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 a.m. (local time) as the Easter Sunday mass were in progress, police spokesman Ruwan Gunasekera said.

Explosions were reported from three five-star hotels - the Shangri-La, the Cinnamon Grand and the Kingsbury in Colombo. Gunasekera confirmed 207 deaths. However, the News 1st channel said that 215 people have died in the blasts. Chairman of Sri Lanka Tourism Kishu Gomes said 33 foreign nationals have been killed in the coordinated attacks believed to be carried out by a single group. Director of the National Hospital Dr Anil Jasinghe identified 12 of the 33 foreign nationals, which include three Indians, two Chinese and one each from Poland, Denmark, Japan, Pakistan, America, Morocco and Bangladesh.

External Affairs Minister Sushma Swaraj, in a series of tweets, identified the three Indians as Lakshmi, Narayan Chandrashekhar and Ramesh. "Indian High Commission in Colombo has conveyed that National Hospital has informed them about the death of three Indian nationals," she said in a tweet. Around 500 people, including Indians, were injured in the attacks. No group has claimed responsibility for Sunday's attacks. Briefing reporters, Gunasekera said the police was not able to confirm at the moment if they were all suicide attacks. He, however, said that one of the blasts at the Katuwapitiya (Negombo) church has signs of being what looked like a suicide attack.