Israel has launched retaliatory air strikes on Palestinian militant targets after dozens of rockets slammed into Israeli towns, injuring five people.
Israeli aircraft carried out attacks on Hamas arms factories and the Gaza Strip field used by militants to launch their rockets. Israel also sealed off the West Bank and Gaza and amassed troops along its border with Gaza. An airstrike on a car in Gaza City killed at least two Palestinian militants.
Israel's defense minister, Shaul Mofaz, has promised a "crushing" response to Hamas, and an emergency meeting of Israel's security cabinet has been called for Saturday evening.
Hamas threatened more attacks inside Israel, and militants fired at least three more rockets into an Israeli town, Sderot, injuring one person.
The escalation follows an explosion at a Hamas military parade Friday that killed 15 Palestinians and injured 80 others. Hamas blamed an Israeli missile attack, but Israel denied involvement. The Palestinian Authority blamed Hamas for mishandling explosives.