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
The boy named by Hamas was Yunes Abu Daqqa was hit by rounds fired by an Israeli army helicopter. He was reportedly killed on Thursday when clashes erupted after militants opened fire on Israeli forces that had entered Gaza.
“Terrorists opened fire at IDF [Israeli Defence Forces] soldiers while they were performing routine activity adjacent to the security fence,” Israel’s military spokeswoman Avital Leibovich said.
The AFP news agency quoted Hamas health ministry spokesman Ashraf al-Qudra as saying the boy, Yunes Abu Daqqa, “was killed by bullets fired from an Israeli helicopter during an incursion” in southern Gaza.
Soon after, a large tunnel blew up near the border fence, throwing a military vehicle 20m (65ft) into the air and injuring the soldier, said Israeli military spokeswoman Lt Col Avital Leibovich.
The tunnel was one of the biggest seen in recent years, she said, and could have been part of a plan to kidnap or kill soldiers.
Hamas’ military wing, the Izz al-Din Qassam Brigades, said it caused the blast, in response to the killing of the boy.
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.