premise: Israeli Defense Minister Amir Peretz Wednesday vowed to revenge an earlier Palestinian militants ' rocket attack that killed a woman in southern Israel, saying the militants behind the attack would "pay a heavy price".
  Peretz made the warning in a statement, reported the Qatari al- Jazeera TV channel.
  "These organizations will pay a heavy price," the statement said, adding "we will move against those who are involved in the firing of rockets, starting from their leaders and down to the last of their terrorists."
  It was reported that Peretz has planned to convene a special meeting of senior security officials later in the day.
  An Israeli woman was killed and another man seriously wounded on Wednesday morning as six Qassam rockets, launched from the Gaza Strip, fell in the southern Israeli city of Sderot, local media reported.
   What caused a woman to be killed?
hypothesis: Palestinian militants ' rocket attack