The commander of Hamas's military wing, Mohammed Odeh, has been killed in a strike in the Gaza Strip on Tuesday - days after his predecessor died in a similar attack.
At least three Palestinians were killed and dozens more were injured in the attack, which hit a residential building in one of Gaza City's busiest market areas, local medics and witnesses said.
Israel's military and Shin Bet security service and said buildings that served as a hideout for Odeh were targeted after his movements were tracked for several months.
Hamas has yet to issue an official statement, but a local Hamas source and relatives said Odeh and his wife were killed along with their adult son.
Despite the Israel-Hamas ceasefire agreed in October, violence in Gaza has continued on a near-daily basis.
Tuesday's strike hit the upper three floors of the al-Kayali building in the centre of Gaza City, where streets were busy with shoppers ahead of the Muslim holiday of Eid al-Adha.
Rescue teams rushed to the scene of the strikes but struggled to reach the upper floors because of the scale of the damage and congestion in the area.
Witnesses said at least five missiles struck the building almost simultaneously from different directions.
One resident said he heard the sound of a helicopter hovering overhead before the attack.
Footage from the scene showed ambulances and civil defence crews searching through the damaged building as crowds gathered nearby.
A statement from the Israel Defense Forces (IDF) and Shin Bet said: "As part of the joint operation by the IDF and Shin Bet to eliminate the terrorist Mohammed Odeh, several buildings in the heart of Gaza City that served as a hideout for him were attacked, after months of intelligence surveillance in order to track his movements and the movements of his assistants in the organisation."
They added that they had also struck "a nearby apartment belonging to a Hamas terrorist who raided on October 7 and was part of Odeh's circle of assistants", referring to the Hamas-led attack on southern Israel that triggered the war in Gaza.
A local Hamas source later told the BBC on Tuesday that Odeh and his wife had been killed.
Their family said Odeh's son died of his wounds in hospital on Wednesday morning and that a funeral would take place after noon prayers at a mosque in Gaza City.
A statement from Israeli Prime Minister Benjamin Netanyahu's office said on Tuesday that Odeh was "one of the architects of the October 7 massacre".
"Odeh was responsible for the murder, abduction, and wounding of many Israeli citizens and IDF soldiers," it continued.
Odeh's predecessor as commander of the group's armed wing, Izz ad-Din al-Haddad, was killed in another Israeli air strike earlier in May.
That attack also targeted a residential building and killed at least three people, according to eyewitnesses and a local source.
Israel has conducted regular strikes across Gaza since a ceasefire began on 10 October.
Hamas has repeatedly accused Israel of breaching the terms of the ceasefire and attacking civilians. The Palestinian territory's Hamas-run health ministry has reported the killing of more than 900 people in Israeli strikes during the ceasefire.
Israel's government maintains it has the licence to target Hamas members and has in turn accused Hamas of breaching the ceasefire agreement by failing to disarm.
The latter phases of a US-led peace plan for Gaza have yet to come into force, with progress stalling since the US and Israel started a war with Iran in February.
The US announced the start of the second phase of the plan in January, with governance of Gaza assumed by a transitional, technocratic administration alongside the demilitarisation and reconstruction of the territory.
However, talks on disarmament remain deadlocked, while Hamas has since reactivated its police force and appears to be reasserting its authority.
Israeli Defence Minister Israel Katz said on Wednesday that Israel was committed to preventing Hamas from governing Gaza "either civilly or militarily".
He also said that what he called the "plan for voluntary emigration from Gaza" would be implemented "at the proper time and in the proper manner".
In his statement, Netanyahu said Israel would "continue to pursue anyone who took part in the October 7 massacre", adding: "Sooner or later, Israel will reach them all."
About 1,200 people were killed in the Hamas-led attack and 251 others were taken hostage.
Israel responded by launching a massive military campaign in Gaza, which reduced much of the Palestinian territory to ruins and left many of its 2.1 million residents displaced.
Israeli forces have killed more than 72,800 people in Gaza, according to its health ministry, whose figures the UN considers reliable.
The latest Israeli attack on Gaza comes after 31 people were killed by Israeli strikes in Lebanon, where Netanyahu has vowed to step up military action against the armed group Hezbollah. Israel's military said its attacks targeted Hezbollah infrastructure and fighters.
