An 18-year-old Palestinian wounded by an Israeli strike in Gaza's Jabalya refugee camp last week died in a Tel Aviv hospital on Sunday.
A second teenager, Abdallah Abu Namous, 16, died as a result of fresh Israeli attacks. Three people were also wounded in the attacks.
Abu Namous entered an area in northern Gaza that has been under attack from the Israeli army countering rocket fire from Palestinian fighters.
The Israel army claims that Israeli forces were targeting a Palestinian fighter who had launched three homemade rockets into Israel earlier the same day.
According to Palestinian security officials, Abu Namous had entered the area accidentally.
Since the beginning of November, 98 Palestinians have been killed by the Israeli army, almost all of them in northern Gaza.
The bloodiest day of fighting in northern Gaza came last Wednesday, when an Israeli artillery shell killed 18 civilians in the northern Gaza town of Beit Hanoun.
The teenagers' death brings the number of people killed since the start of the second Palestinian uprising in September 2000 to 5,560. The majority of whom have been Palestinians.