JERUSALEM/GAZA/DOHA/SYROS,Greece - About 300,000 people have fled Gaza City as Israel intensified strikes, Israel's Army Radio reported on Sunday, citing security officials.

Israeli attacks, mainly in the northern Gaza Strip, killed at least 68 Palestinians and wounded 346 others in the past 24 hours, Gaza's health ministry said on Sunday.

The strikes destroyed at least two multi-storey buildings in Gaza City, including one belonging to the Islamic University that was sheltering displaced people. Israeli Defense Minister Israel Katz shared a video on social media showing the university building being bombed and collapsing.

The Israeli military confirmed it had struck two high-rise buildings, claiming Hamas used them for intelligence gathering and surveillance.

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Israel says it plans to take over Gaza City, where about a million people had been living and sheltering before the offensive began, as part of its declared aims to dismantle Hamas and release almost 50 hostages held by the group.

US Secretary of State Marco Rubio arrived in Jerusalem on Sunday and visited the Western Wall along with Israeli Prime Minister Benjamin Netanyahu. The two are scheduled to hold talks.

Netanyahu called Rubio "an outstanding friend of the State of Israel" and said his visit showed "the resilience of the alliance between the United States and Israel."

"Under President Trump and Secretary of State Rubio, this alliance is stronger than ever," Netanyahu said.

Speaking to reporters before departing for Israel, Rubio said Trump was "not happy" about the Israeli strike in Qatar on Tuesday but that it would "not change the nature of our relationship with the Israelis." He added the two countries would "have to talk about" the impact on prospects for a ceasefire deal.

Rubio is due to visit a settlement excavation site on Monday, run by the pro-settler Elad organization in the Palestinian neighborhood of Silwan in East Jerusalem.

Israel's military operations have killed more than 64,000 people in Gaza since October 2023, according to Gaza's health authorities, with much of the enclave reduced to rubble and famine spreading.

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Also on Sunday, Israel launched intensive airstrikes on neighborhoods in western Gaza City, killing at least seven Palestinians and wounding several others, Palestinian sources said.

Local eyewitnesses told Xinhua that the airstrikes hit Al-Kawthar Tower, the upper floors of Muhanna Tower, and several multi-storey residential buildings. They added that the Israeli military also targeted the "Falasteen" camp for displaced people, which shelters dozens of tents, along with nearby houses and facilities, the Islamic University, the Community College in the Tel al-Hawa neighborhood, and surrounding residential blocks.

Sources from Gaza's health authorities said seven Palestinians were killed in an airstrike on a residential building near Barcelona Park in Tel al-Hawa. Several others were injured, some critically, and taken to hospitals for treatment.

Heavy plumes of smoke rose over destroyed buildings as civil defense teams worked to rescue people from the rubble, video footage on social media showed.

In a press statement, the Israeli army said its fighter jets targeted "sites used by Hamas for military operations and intelligence purposes," stressing that warnings were issued to residents ahead of certain strikes.

The Hamas-run government media office in Gaza accused the Israeli military of carrying out a "systematic bombardment" of residential towers, schools, and civilian institutions aimed at "forcible displacement," and urged the international community to intervene.

Prisoner swap talks suspended

Hamas said on Sunday it had suspended talks on a prisoner swap with Israel after accusing Israel of targeting its negotiating delegation in the Qatari capital Doha last week.

"Negotiations cannot continue if the delegation responsible for them is attacked inside the country acting as mediator," Tahir al-Nono, a senior Hamas official, said in a statement.

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Hamas said Israeli airstrikes last Tuesday hit residential compounds in Doha used by its leaders while they were discussing a US-backed ceasefire proposal. The delegation, led by senior Hamas official Khalil al-Hayya, survived, but five Hamas members and a Qatari security officer were killed, the group said.

Al-Nono accused Netanyahu of obstructing efforts to reach both a ceasefire and a prisoner exchange. He warned that intensified Israeli strikes on residential towers in Gaza could endanger Israeli captives held there.

"The only logical solution is for the international community to issue and enforce a decision to stop this war," he said.

Al-Nono also dismissed Rubio's visit to Israel on Sunday, saying Hamas expected no change in Israel's position.

In Doha, Qatari Prime Minister and Foreign Minister Sheikh Mohammed bin Abdulrahman bin Jassim Al-Thani said on Sunday that Israel's recent attack on Doha will not prevent Qatar, Egypt and the United States from continuing their mediation efforts to end the war in Gaza, the Qatar News Agency (QNA) reported.

According to the QNA, the Qatari prime minister made the remarks during a preparatory meeting with foreign ministers from Arab and Islamic countries, held ahead of an emergency Arab-Islamic summit. The foreign ministers discussed a draft statement on the Tuesday attack by Israel on  Doha.

In his talks, Al-Thani stressed that the region cannot achieve comprehensive peace and security unless the Palestinian people obtain their legitimate rights.

Aid flotilla

Meanwhile, Greek sailing vessel Oxygono (Oxygen), part of the Global Sumud Flotilla (GSF), an international convoy seeking to break Israel's blockade of the Gaza Strip and deliver humanitarian aid, set sail from the island of Syros on Sunday.

The mission aims to raise awareness of the suffering of the Palestinian people and help end the conflict that began nearly two years ago, said Vassilis Rogas, a journalist at the Greek newspaper Epochi (Era) and a member of the Greek mission.

Greek activists of various ages and professions departed from Ermoupolis port to join about 1,000 other activists from over 40 countries on board some 60 ships in the Mediterranean international waters en route to Gaza, according to GSF organizers.