Moamen al-Adam died when a missile slammed into a farm in the Zeitun neighbourhood, east of Gaza City.
His father was also seriously wounded in the strike, and two other people were said to be in moderate condition.
The Israeli military had no immediate comment on the latest raid.
It was the second deadly strike in a three-hour period.
An earlier air raid killed 21-year-old Hamas militant Ghaleb Ermilat, whom Israel said was a "global jihad operative" who was behind a deadly ambush along the Israeli-Egyptian border, which killed one Israeli civilian earlier this week.
Ermilat was riding a motorcycle in the southern border city of Rafah when the missile struck.
Since Monday, Israel has staged multiple raids across Gaza, while militants from armed wing of the ruling Hamas movement have fired scores of missiles at the Jewish state, in a rare departure from the de facto truce the group normally observes. (*)
Editor: Kunto Wibisono
Copyright © ANTARA 2012
