GAZA CITY — Hamas militants in Gaza bombarded a major southern Israeli city with rocket fire Friday, continuing a week of tit-for-tat fighting that threatens to destroy a tenuous cease-fire.
Israel and the Gaza Strip's Hamas rulers held out hope that calm would be restored, and Israeli leaders decided against any immediate major retaliation. But both sides vowed to strike back hard if violence persisted.
"If you want to leave the truce, we are ready. And if you want to continue it, then abide by it," Hamas strongman Mahmoud Zahar said in a Friday sermon.
The truce took effect in June, largely halting a cycle of Palestinian rocket attacks on southern Israel and deadly Israeli reprisals.
The cease-fire mostly held, but it began to deteriorate last week after an Israeli raid on what the army said was a tunnel that militants planned to use for a cross-border operation. Eleven militants have been killed, and Palestinians have fired about 140 rockets and mortar rounds at Israel.
Israel also has shut Gaza's vital border crossings, blocking the entry of food, humanitarian goods and fuel into the impoverished area.
Friday's rocket barrage was one of the heaviest yet. Nearly 20 rockets were fired into southern Israel, including four Grad-type Katyushas that landed in Ashkelon, about 17 miles north of Gaza. One woman in the town of Sderot was lightly injured by shrapnel, the army said.
The foreign-made Katyushas are believed to be smuggled into Gaza and have longer ranges than the crude homemade rockets usually fired by militants.
With 120,000 people, Ashkelon is the biggest population center in rocket range, and Israel has responded harshly to past attacks on the coastal city.
But Israeli defense officials said the government had decided against any major military action for the time being unless the situation deteriorated. The officials spoke on condition of anonymity because they were discussing classified information.
"We will keep protecting our soldiers and people and keep acting against attempts to interrupt the cease-fire, but if the other side will want or wish to keep the cease-fire alive, we'll consider it seriously," Defense Minister Ehud Barak said.
The barrage came in response to an earlier Israeli airstrike that wounded two militants as they attempted to fire rockets.
By sundown, the sides appeared to be pulling back, and the area settled into relative calm.