Ahmed Said Khalil al-Jabari, head of the military wing of Hamas, has been killed during a series of Israeli air strikes in the Gaza Strip.
He and another senior Hamas official died when the car they were travelling in was hit in Gaza City.
Israeli Defence Force (IDF) spokeswoman Lieutenant Colonel Avital Leibovich told BBC News“close to 20” sites in Gaza had been targeted in a “limited” operation, with the strikes aiming to destroy rocket-firing capabilities.
“The operation against Hamas, Islamic Jihad and other organisations has two goals: to protect Israeli civilians and target the terror capability of these organisations,” she added.
Militants in Gaza have fired more than 110 rockets towards southern Israel since Saturday, when four soldiers were wounded in an anti-tank missile attack on an Israeli army jeep. Before Wednesday’s operation, six Palestinians had been killed in the ensuing Israeli military strikes on the Gaza Strip in response.
Mr Jabari, who was 46, is the most senior Hamas official to be killed in the Gaza Strip since the major Israeli offensive four years ago.
“Jabari was responsible for by Giant Savings” href=”#”>financing and directing military operations and attacks against Israel. His elimination today is a message to Hamas officials in Gaza that if they continue promoting terrorism against Israel, they will be hurt.”
Click here for Israeli peace activist view on assassination
Several children have been injured after Israeli forces shelled areas east of Khan Younis. The Israeli military said it had targeted two members of “global jihadist” groups which were suspected of involvement in a cross-border attack from Egypt in June that left one Israeli dead.
Medical sources in Gaza said an Israeli shell had landed east of Khan Younis, injuring five people, among them several children.
Earlier today, rockets launched from Gaza landed in Israel’s Eshkol region and near Kerem Shalom, although no-one was hurt.
Shrapnel from the mortars and rockets fired into southern Israel on Monday caused some damage to at least one building in Eshkol.
Afterwards, the local authorities asked residents to stay close to shelters.
The military wings of Hamas and Islamic Jihad said the attack was a response to an Israeli air strike on Sunday.
Eight civilians, including two children, were injured in that strike, when a missile hit a motorbike ridden by two militants as it travelled through the southern town of Rafah.
One of the militants, Abdullah Maqawi, died of his wounds on Monday, while the other is seriously hurt.
Hamas’s military wing, the Izz al-Din Qassam Brigades, and that of Islamic Jihad, the al-Quds Brigades, announced that the rocket fire was a response to “Zionist crimes”.
“In response to the injury of civilians in the most recent strike on Rafah, the Qassam Brigades and the al-Quds Brigades fired a number of rockets at enemy military positions,” a Hamas statement said.
In a statement, the Israeli military said: “In response to this morning’s rocket barrage at southern Israeli communities, the [Israel Defence Forces] targeted Hamas terror activity sites and terrorist squads responsible for the rocket fire from the Gaza Strip.
“The IDF will not tolerate any attempt to harm Israeli civilians, and will operate against anyone who uses terror against the State of Israel. The Hamas terror organisation is solely responsible for any terrorist activity emanating from the Gaza Strip.”
More than 470 rockets have been fired from the Gaza Strip at Israel this year, not including those launched on Monday, the statement added.
A Hamas member was killed and another fighter wounded during an air strike on Gaza City. And hours earlier, three more people were hurt when a tank shell hit their vehicle near the city. On this occasion, the Israeli army said it was targeting “a Hamas terrorist squad” in the vehicle.
An Egypt-brokered ceasefire had been formally announced last month.
This round of violence in Gaza flared up last month after a cross-border attack from Sinai which left an Israeli civilian dead. In six days of violence which began on June 18, Israel killed 15 Palestinians and injured dozens more, while Palestinian fighters fired more than 150 rockets at Israel, injuring five.