The soldier is the first casualty for the armed forces since the operation to flush out the Sulu gunmen who landed in Kampung Tanduo on Feb 12.
Eight police officers were killed in previous skirmishes with the gunmen. Armed Forces chief Tan Sri Zulkifeli Mohd Zin said the joint military and police forces were conducting mopping and searching operation at 7.45am on Tuesday.
“They had a gun fight with five armed men who then retreated,” he told a press conference about 15km from where the shootings occurred.
Jen Zulkifeli said security forces tracked down the group and engaged in another gun fight at 10.45am.
“In the exchange of fire a soldier and three terrorists were killed,” he said.