Tel Aviv, Jan 23 : At least 21 Israeli soldiers have been killed in Gaza while fighting Hamas, the Israel Defense Forces said on Tuesday. Addressing a press briefing, IDF spokesman Daniel Hagari said soldiers were preparing explosives to demolish two buildings when militants launched a rocket-propelled grenade at a nearby tank on Monday, triggering a premature explosion that resulted in the collapse of the buildings while the soldiers were either inside or nearby, Xinhua news agency reported. Offering condolences to the families of the soldiers who died, Israeli Prime Minister Benjamin Netanyahu posted on X: " I wish to strengthen the dear families of our heroic warriors who fell on the battlefield. I know that for these families, their lives will be changed forever. Prime Minister Netanyahu said the millitary has launched an investigation into the incident. /IANS