Militants in the Gaza Strip have fired more than 150 rockets into Israel, the army says, prompting air strikes and tank fire on the Palestinian territory.
Sirens went off as people rushed to shelters in southern israel. Two Israelis were wounded and a Palestinian man was killed in the exchange.
Four Palestinians, including two Hamas militants, were killed on Friday after an attack injured two Israeli soldiers.
The flare-up followed a truce in the run-up to Israeli elections in April.
It marks yet another increase in hostilities despite attempts by Egypt and the United Nations to broker a longer-term ceasefire, says the BBC's Tom Bateman in Jerusalem.
What happened on Saturday?
The rocket barrage sent Israelis scrambling for safety. Media showed pictures of damage to homes about 10km (six miles) north of Gaza.
The injured include a man in Ashkelon and an elderly woman in Kiryat Gat, further east.
The country's Iron Dome missile-defence system shot down dozens of the rockets, the Israel Defense Forces (IDF) said.
