According to Sri Lankan Police, at least three militants set off explosives at a Daesh hideout, killing three women and six children inside the building.
"Three other men, also believed to be suicide bombers, were found dead outside the house", the statement added, noting that the suspects had been shot.
There is a total of 15 people dead during the operation, with no casualties among the security forces, the police said.
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Earlier it was reported that three civilians were wounded in the gunbattle that saw at least three explosions, according to AP citing Major General Aruna Jayasekara, the local military commander.
"Three other men, also believed to be suicide bombers, were found dead outside the house", police said in a statement.
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The military said security forces have also recovered explosives, detonators, "suicide kits," military uniforms and Daesh flags during the raids on a location believed to have been used for the manufacture of suicide vests.
"We have found the backdrop the group used to record their video", the police said in an earlier statement on Friday night.
Earlier this week, the US Embassy in Colombo issued an alert warning of more possible upcoming attacks this weekend, urging citizens to stay away from places of worship and large crowds.
*Daesh (also known as IS, ISIS, ISIL) is a terrorist group, banned in numerous countries, including Russia.