Fighting between Israel and Palestinian militants in Gaza appears to have calmed after an unofficial truce was reached following days of violence.
Israel said a mortar shell landed in the south of the country on Thursday after no reports of exchanges fighting.
Five people have been wounded in Israel since Tuesday amid some of the heaviest barrage of rocket and mortar fire from Gaza in months.
Six Palestinian militants were killed in Israeli air strikes on Gaza.
Schools were closed on both sides of the border for fear of more attacks, though some reopened in parts of southern Israel on Thursday.
Prime Minister Benjamin Netanyahu vowed to strike hard at the militants if attacks continued.
"We didn't ask for this escalation and didn't initiate it," he said on Wednesday. "But if it continues, we are prepared to embark on a far more extensive and penetrating operation."
If previous ceasefires are anything to go by, there may well be breaches by both sides before calm is fully restored, says the BBC's Jon Donnison in Gaza.
Hamas will have to stop other armed groups in Gaza from launching attacks, and the underlying conflict between Palestinian militants and Israel remains; any truce is unlikely to be permanent, our correspondent adds.
On Wednesday, more than 70 rockets were launched into southern Israel, injuring four people, two critically, according to the Israeli military.
In response, Israeli aircraft and tanks targeted rocket-launching sites in northern Gaza.
Hamas's military wing, the Izz al-Din Qassam Brigades, confirmed it had been involved in firing dozens of rockets and mortars into Israel.
In a statement, the Izz al-Din Qassam Brigades and a smaller Gaza-based militant group, the Popular Resistance Committees (PRC), said: "These holy missions come in response to the repeated, continuous crimes of the enemy against our people."
The violence comes during a visit to the region by the EU's foreign policy chief, Catherine Ashton, to try to revive the stalled Middle East peace process.
She is due to meet Palestinian Authority President Mahmoud Abbas and his Prime Minister, Salam Fayyad on Thursday, a day after holding talks with Israeli leaders.