COLOMBO, Sri Lanka—Sri Lankan security forces found 15 bodies, including six children, early Saturday after militants linked to the Easter bombings opened fire and set off explosives during a raid on their house in the country’s east, police said.

The gunbattle began Friday night after police tipped off soldiers to a suspected safe house near the town of Sammanthurai , where authorities said the militants detonated three explosions and opened fire. At least three others were wounded in the attack, said police spokesman Ruwan Gunasekara.

He said that some of the dead likely were militants who blew themselves up in suicide bombings. Earlier, the military said at least one civilian had been killed in the attack.

Raids and police curfews shut down areas of eastern Sri Lanka as Catholic leaders cancelled Sunday Masses indefinitely. Officials also urged Muslims to stay home for prayers in an extraordinary call by the clergy to curtail worship as fear of more attacks plagued the island nation.

Maj. Gen. Aruna Jayasekara, the local military commander, said soldiers and police waited until daylight Saturday to carry out further raids in Eastern Province given houses being built so close together.

Meanwhile, the military said security forces had recovered explosives, detonators, “suicide kits,” military uniforms and Islamic State group flags in the ongoing raids.

In the same area, police spokesman Ruwan Gunasekara said officers acting on information from intelligence officials found 150 sticks of blasting gelatin and 100,000 small metal balls, as well as a van and clothing suspected to be used by those involved in the Easter attack. Suicide bomb vests often are packed with such balls to increase the shrapnel in the explosion, making them even deadlier.

Officials from the police to the prime minister say militants remain on the loose and have access to explosives. That has led to increased security at shrines, churches, temples and mosques across the multiethnic country of 21 million off the southern coast of India.

Cardinal Malcolm Ranjith told journalists Friday that church officials had seen a leaked security document describing Roman Catholic churches and other denominations as a major target. Ranjith, who is the archbishop of Colombo, asked the faithful across Sri Lanka to stay home for their own safety.

“We don’t want repetitions,” Ranjith said.

It was an extraordinary request for a Catholic clergyman to make, as churches often remain a refuge. Giovanni Maria Vian, a church historian and emeritus editor of the Vatican newspaper, said he believed it was the first time the church had cancelled Masses across a country for security reasons.

On Saturday, cleaning crews arrived to St. Anthony’s Shrine in Colombo, where broken glass still littered a blood-stained floor. They collected debris, tossing it into a truck parked outside as a heavy contingent of security forces stood guard.

The U.S. Embassy in Sri Lanka has warned the public to stay away from places of worship over the weekend, a stark alert underlining that authorities believe that attackers remain at large.

Authorities told Muslims to worship at home rather than attend communal Friday prayers that are the most important religious service of the week, but several mosques held services anyway. At a mosque in Colombo, police armed with Kalashnikov assault rifles stood guard outside for hundreds of worshippers as the imam inside and others wept while praying to Allah to help their country.

The Easter attackers are “not Muslims. This is not Islam. This is an animal,” said Akurana Muhandramlage Jamaldeen Mohamed Jayfer, the chairman of the mosque. “We don’t have a word (strong enough) to curse them.”

Sri Lanka’s government, crippled from a long political crisis between the president and prime minister last year, promised swift action to capture militants still at large. President Maithripala Sirisena said about 140 people had been identified as having links to the Islamic State group.

A “major search operation has been undertaken,” Sirisena said. “Every household in the country will be checked.”

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Earlier Friday, police confirmed the militant group’s leader, Mohamed Zahran, died in the suicide bombing at the Shangri-La Hotel, one of six hotels and churches attacked. Zahran appeared in an Islamic State video claiming responsibility for the co-ordinated assault, and authorities in both Sri Lanka and Australia confirmed links between IS and the attack.

On Thursday night, Sri Lanka’s Health Ministry drastically reduced its estimated death toll from the bombings. A statement said “approximately” 253 people had been killed, nearly one-third lower than an earlier police estimate of 359 dead.

The discrepancy was not immediately explained, but it fit a pattern of confused reports by Sri Lankan officials that have muddled the investigation. On Friday, police apologized to a Brown University student and a human rights activist after they posted her picture to Twitter and erroneously identified her as a wanted militant. The police then deleted their Twitter account.