Jerusalem (AFP) - Israeli aircraft struck Hamas bases in Gaza early Friday, the military said, after a rocket fired by Palestinian militants hit a Jewish theological seminary in southern Israel.
There were no reported casualties on either side.
"Last night, a rocket was launched from the Gaza Strip into Israeli territory," Friday's military statement said.
It said that in response the Israeli Air Force "fighter jets and aircraft targeted terror infrastructure in military compounds and a Hamas naval force military compound as part of a strike on a number of Hamas terror sites throughout the Gaza Strip."
The seminary, in the town of Sderot, was empty at the time of the rocket attack as students had left to return to their homes elsewhere to celebrate the Jewish sabbath -- which begins on Friday-- with their families.
Israeli police said the building was damaged when it was hit "with full force".
The Sderot incident came hours after Israeli warplanes bombed bunkers at a Hamas base in southern Gaza on Thursday, causing no casualties, according to a Palestinian security source.
That strike came after Israeli air defences intercepted a previous rocket launched from Gaza, the first since hundreds were fired from the enclave in early May in a flare-up which killed 25 Palestinians and four Israelis.
On Friday, some 6,500 Palestinian "rioters and demonstrators" gathered along the Gaza border fence as part of the weekly protests, throwing rocks and explosive devices at soldiers, the Israeli army said.
The troops "responded with riot dispersal means and fire in accordance with the standard operating procedures," a spokeswoman said.
The Gaza health ministry said 46 civilians and three paramedics were wounded in the clashes.
Also Friday, incendiary balloons launched from Gaza caused seven fires in Israel, reports said.
In the past year, Palestinians have succeeded in setting fire to large areas of farmland in southern Israel.
On Wednesday Israeli authorities announced a ban on fishing off Gaza, in response to the launching of balloons, fitted with incendiary devices, into Israeli territory to set fire to farmland.
Gaza's Islamist rulers Hamas and Israel have fought three wars since 2008.
And there are mounting concerns that another flare-up could occur ahead of Israel's September 17 elections.
The Israeli army said Friday it "holds Hamas responsible for all events transpiring within the Gaza Strip and emanating from it".