SAINTHAMARUTHU/COLOMBO, Sri Lanka (Reuters) - As darkness fell in Sainthamaruthu village on Sri Lanka’s east coast on Friday, troops and police prepared to storm a concrete shack that local residents had told them was a safe house for a band of Islamist militants.

It was five days after suicide bomb blasts that killed more than 250 people and stunned a country that few expected to be a target of Islamist attacks. Many of the dead in Sunday’s attacks were killed in Batticaloa, a town about 28 miles (46 km) north of Sainthamaruthu.

On Friday evening, as the troops approached the house - a one-storey building on a narrow lane opposite an open drain - three explosions went off and they opened fire on the suspects holed up inside, according to the military.

The wife and a daughter of the suspected mastermind of the suicide attacks, Mohamed Hashim Mohamed Zahran, were wounded in the ensuing gunbattle, police and his sister said on Saturday.

Nearly 10,000 soldiers have been deployed across the island to carry out searches since the Easter Day attacks on three churches and four hotels, most of which were in the capital Colombo. Security forces have detained 100 people, including foreigners from Syria and Egypt.

Islamic State has claimed responsibility for the bombings on the Buddhist-majority country, which would be one of the worst attacks carried out by the group outside Iraq and Syria.

The Friday night shootout in the Muslim-dominated district of Ampara followed warnings from authorities that there were still militants at large plotting further strikes. The militants hiding there were suspected members of a domestic Islamist group, National Thawheedh Jamaath, the military said.

Security personnel seen at the site of an overnight gun battle between troops and suspected Islamist militants, on the east coast of Sri Lanka, in Kalmunai, April 27, 2019. REUTERS/Dinuka Liyanawatte

The gunbattle ended before dawn, and as troops moved in on the ruined house they found the bodies of 15 people, including six children and three suspected suicide bombers, a military spokesman said.

A large cache of explosives were found at the house, he said.

The road outside was strewn with shoes and debris, and spattered with blood, said a Reuters witness, who saw bodies wrapped in cloth and body parts being carried away in fertilizer bags.

Villagers had noticed unusual activity at the house on Friday, a resident told Reuters, adding that the suspected militants spoke arrogantly and refused to reveal their identity.

“One of the persons in that house came for prayer to the mosque and he looked so suspicious,” the resident said, who declined to be named because he feared for his own safety.

The villagers went back to the house a second time, this time with a government official, but the suspects opened fire. They then informed the police, he said.

After the shooting was over, about 500 village families were evacuated as troops began a seven-hour search of the area.

“We never experienced this kind of scare, even during the LTTE war,” the resident told Reuters over the phone, referring to the 26-year conflict between government forces and ethnic Tamil separatists that ended a decade ago.

As the door-to-door search of the village continued, a soldier emerged from one house carrying an injured child in his arms. As the child was laid in a military vehicle, she called through tears for her father.

The military said that as the search widened to Sammanthurai village nearby, they found a haul of explosives, detonators, acid bottles, Islamic State flags, suicide kits and military uniforms.