The Hamas-run Gaza government media office also said dozens were wounded and missing in the strikes. Medics said the air strikes targeted a multi-floor building and damaged several houses nearby.
There was no immediate Israeli comment.
Palestinian health officials said rescue operations were being hampered by the cut-off of telecommunication and internet services for the second day.
An explosion from an Israeli air strike targeting a nearby building in Beit Lahiya (file photo). (AP PHOTO)
Earlier in the day, the Gaza health ministry said Israeli military strikes killed 35 Palestinians across the enclave.
"This is a war of genocide and ethnic cleansing. The occupation has conducted a horrifying massacre in Beit Lahiya," the Hamas media office said.
Israel struck what it says were Hezbollah arms facilities in southern Beirut after the Lebanese armed group fired rockets into northern Israel while a spokesman says a drone was launched at Prime Minister Benjamin Netanyahu's holiday home.
Netanyahu was not there at the time, his spokesman said, and it was not immediately clear if the building was hit.
But the prime minister said what he called an attempt to assassinate him and his wife was a "grave mistake".
The attempt by Iran's proxy Hezbollah to assassinate me and my wife today was a grave mistake. — Benjamin Netanyahu - בנימין נתניהו (@netanyahu) This will not deter me or the State of Israel from continuing our just war against our enemies in order to secure our future. I say to Iran and its proxies in its axis of evil:…October 19, 2024
The strikes came as health officials in Gaza, where Israel has been trying to root out Palestinian militant group Hamas for more than a year, said Israeli bombardments had killed at least 35 people and a siege around three hospitals had tightened.
Promises by Israel and its enemies Hamas and Hezbollah to keep fighting have chilled hopes that the death of Hamas leader Yahya Sinwar on Wednesday might lead to truces in Gaza and Lebanon and prevent further escalation in the Middle East.
Officials, diplomats and other sources say that with US elections approaching, Israel is seeking to use intensified military operations to try to shield its borders and ensure its rivals cannot regroup.
On Saturday, Israeli planes dropped leaflets over southern Gaza with a picture of Sinwar and the message: "Hamas will no longer rule Gaza".
In Beirut's southern suburbs, Israel carried out heavy strikes on several locations, leaving thick plumes of smoke hanging over the city into the evening.
The strikes targeted "a number of Hezbollah weapons storage facilities and a Hezbollah intelligence headquarters command centre", Israel's military said.
Israel had issued evacuation orders for four separate neighbourhoods within the suburbs, urging residents to get 500 metres away, but carried out strikes in other areas as well, witnesses said.
Tens of thousands of people have fled the southern suburbs - once a densely populated zone that also housed Hezbollah offices and underground installations - since Israel began regular strikes there about three weeks ago.
The United States would like to see Israel scale back some of its strikes in and around Beirut, US Defense Secretary Lloyd Austin said.
Since October 2023 more than 2400 people have been killed in Lebanon, most of them in the last month, according to Lebanon's health ministry, while 59 people have been killed in northern Israel and the occupied Golan Heights, according to Israeli authorities.
Hamas-led militants killed some 1200 people and took 250 hostage in the attack that triggered the war, according to Israeli tallies.
Israel's military response has left more than 42,500 people dead, Palestinian officials say.
The Israeli offensive has made most of Gaza's 2.3 million people homeless, maimed tens of thousands, caused widespread hunger and destroyed hospitals and schools.
US Secretary of State Antony Blinken is expected to travel to Israel on Tuesday. (AP PHOTO)
COGAT, the Israeli military agency that oversees administration in the Palestinian Territories, has stepped up deliveries of aid into Gaza amid international pressure.
Western leaders, including US President Joe Biden, have said Sinwar's death offered a chance for a deal for a truce in Gaza and the release of the remaining hostages.
Negotiations for such a deal have been stalled for weeks.
US Secretary of State Antony Blinken, who has led diplomatic efforts, is expected to travel to Israel on Tuesday as part of a regional tour, Axios reporter Barak Ravid said on social media platform X.
