Gaza militants fired rockets at southern Israel on Monday, in violence that tested a shaky truce brokered by Egypt after a border flare-up that has claimed the lives of a dozen Palestinian gunmen and an Israeli civilian since the weekend.
An Israeli military spokeswoman said four rockets slammed into the Ashkelon and Beersheba regions as darkness fell on Monday, while a fifth was intercepted by a missile defence shield which witnesses said set off a loud explosion.
There were no reported injuries.
Israel, saying it had targeted a rocket-firing squad, killed two militants with an air strike in southern Gaza just after midnight on Monday.
Prime Minister Benjamin Netanyahu, addressing parliament at the opening of its winter session, said Israel would use its force and determination against militants and follow a policy that if someone rises us to kill you, you kill him first.
There were no immediate claims of responsibility issued for Monday's rocket fire. More than three dozen other rockets fired at Israel since the weekend were claimed by the Iranian-allied Islamic Jihad group, a rival of Gaza's Hamas Islamist rulers.
The latest round of violence began when Israel, responding to rocket fire at the city of Ashdod on Wednesday which set off sirens as far as the southern reaches of Tel Aviv, attacked Islamic Jihad bases in the Gaza Strip with aerial strikes on Saturday, killing nine gunmen.
Islamic Jihad fired more than 30 rockets at Israel on Saturday and Sunday, killing an Israeli man in the city of Ashkelon and injuring at least two other people.
Egyptian officials who are often involved in efforts to mediate between Israel and the gunmen who have no direct contact with the Jewish state, said Sunday they were able to get both sides to agree to a cease-fire.
There had earlier been a relatively long lull in border violence in the run-up to a prisoner swap on October 18 in which Israel released 477 Palestinian prisoners in exchange for Gilad Shalit, an Israeli soldier held by Hamas since 2006.
(Reporting by Nidal al-Mughrabi and Ari Rabinovitch; Writing by Allyn Fisher-Ilan; Editing by Jon Hemming)