Aid organisation freezes its work in Gaza after two of its staff are abducted.
Another 19-year-old civilian was killed when Israeli tanks firing machineguns stormed a housing project in Beit Lahiya.
Hamas claimed responsibility for the attempted suicide bombing and identified the woman as Fatima al-Nejar, a mother-of-nine.
The objective was then broadened to target rocket-launching squads, who have killed two Israelis in the past week. Fighters say the rockets are a response to army assaults.
Israel has killed nearly 380 Palestinians in Gaza, about half of them civilians, since it began the offensive, hospital officials and residents say. Three soldiers have been killed.