An IDF reservist was killed and three other soldiers were wounded on Friday after an explosive device they encountered detonated in southern Lebanon, just hours after a ceasefire with Hezbollah took effect, the military said Saturday.

The murdered soldier was identified as Warrant Officer (res.) Barak Kalfon Hy’d, 48, of the 226th Reserve Paratroopers Brigade’s 7056th Battalion, from Adi in northern Israel. He worked as an engineer at Rafael and is survived by his wife and two daughters.

His death came Friday following the start of a 10-day ceasefire between Israel and Hezbollah that began at midnight. The reservists had been searching a building in the southern Lebanon village of Jebbayn for weapons.

During the operation, a Hezbollah explosive device detonated, killing Kalfon and wounding three other troops, two moderately and one lightly.

An initial IDF investigation found that the bomb was not remotely triggered and was likely activated automatically.

Kalfon was critically wounded in the blast and airlifted to Rambam Medical Center in Haifa. Despite emergency surgery and extensive life-saving efforts, his death was confirmed several hours after he arrived.

“Next week you would have celebrated 49 (birthday),” said Kalfon’s cousin, Sapir Kalfon, according to Ynet. “What did you achieve? A great deal. Lots. And you didn’t even need to be in uniform anymore. But even so, you insisted on volunteering for reserve duty. That’s who you were. Always with a bright face, always smiling, always embracing and including. Calm, with a heart bursting with goodness.”

The military said the incident remains under investigation. The wounded soldiers were evacuated to a hospital in northern Israel, and their families were notified.

Kalfon was the first Israeli soldier killed in Lebanon since the ceasefire brought a halt to more than six weeks of fighting with the Iran-backed Hezbollah terrorists.

“Barak was a courageous and dedicated fighter and exemplary family man,” Defense Minister Yisrael Katz said in a statement. “In his civilian work as an engineer at Rafael, he contributed significantly to the security of the State of Israel, and combined a first-rate professional sense of duty with significant reserve service and many years of defending Israel.”

He added, “I offer condolences from the depths of my heart to his family at this difficult hour and wish to embrace them.”

Rafael mourned him as a “dedicated and professional employee who dealt with fields significant to the security of Israel, which he loved so.”

Hezbollah began attacking Israel on March 2, shortly after the outbreak of the US-Israeli war with Iran. Israel responded with extensive airstrikes and expanded ground operations deeper into Lebanon.

Including Kalfon, 13 IDF soldiers were killed in southern Lebanon during the fighting. Two civilians were killed by Hezbollah rocket fire, and another Israeli civilian was mistakenly killed in the north by Israeli artillery.

Kalfon was set to be buried Sunday afternoon at the Adi cemetery, according to reports.