Gaza's civil defence agency said Israeli forces killed two teenagers in a drone strike Saturday.
The civil defence agency, which operates as a rescue service under Hamas authority, said the drone killed the two near Kamal Adwan Hospital in Beit Lahia, in northern Gaza.
The territory's Al-Shifa Hospital said it received the two bodies, adding they were two boys aged 13 and 15.
The military said the pair had posed an "immediate threat" to its soldiers.
"Earlier today... troops operating in the northern Gaza Strip identified several fighters who crossed the Yellow Line, planted an explosive device in the area, and approached the troops, posing an immediate threat to them," the military said in a statement.
Under a US-brokered ceasefire that came into effect on October 10, Israeli forces have withdrawn to positions behind a so-called "Yellow Line" in Gaza, though they remain in control of more than half of the territory.
A military press officer told AFP that its troops had "killed two fighters and not children", without specifying the ages of those killed.
The civil defence said another fatality was also reported in a separate incident when an Israeli quadcopter struck a group of civilians in Jabalia, also in northern Gaza.
It did not provide details on the person killed in that incident. The press officer said the military had reports of only one incident.
Israeli forces have killed at least 477 Palestinians in Gaza since the ceasefire took effect, according to Gaza's health ministry, which operates under Hamas authority.
The Israeli army says Palestinian fighters have killed four of its soldiers during the same period.
Media restrictions in Gaza and limited access to many areas mean AFP cannot independently verify casualty figures and details provided by either side.
The ceasefire has largely halted fighting between Israel and Hamas, but both sides have accused each other of violating its terms.