A stream of refugees fleeing Lebanon to Syria crossed a narrow makeshift bridge on foot Sunday in the Qusair area of Syria's Homs province after the official border crossing was put out of commission by an Israeli strike two days earlier.

Only three functioning crossings remain between the countries, which share a border 375 kilometers long.

A Lebanese family was holding a Sunday gathering when an Israeli strike toppled their building.

It was Sunday, family time for most in Lebanon, and Hecham al-Baba was visiting his sister. She insisted he and their older brother stay for lunch, hoping to prolong the warm gathering in stressful times.

The Lebanese health ministry said that Israeli strikes on Sunday killed at least 21 people across southern Lebanon.

Israel launched fresh strikes Monday on Tyre, Lebanese state media said, following an earlier raid that killed seven people.

The National News Agency (NNA) reported "a series of strikes" on the ancient coastal city, beginning with a raid on a residential apartment.

Hezbollah said it fired rockets at a military base in northern Israel on Sunday, a day after it declared several areas in the region a "legitimate target" due to the presence of Israeli troops.

Lebanon's health ministry said at least eight people were killed and 25 others wounded Sunday in an Israeli strike near the southern city of Sidon, where an AFP correspondent said a building was targeted.

The Israeli military on Sunday said four soldiers were killed in southern Lebanon, bringing to 36 the total number of Israeli soldiers killed since the start of ground operations on September 30.

The soldiers "fell during combat in southern Lebanon," the army said in a statement, adding that they were killed on Saturday.

Hezbollah has warned of a "dangerous escalation" in the region, saying Washington bears "full responsibility" for the "treacherous" raids on Iran launched by its Israeli ally.

"Hezbollah strongly condemns the treacherous Zionist aggression against the Islamic Republic of Iran and considers it a dangerous escalation at the level of the entire region," Hezbollah said in a statement.

Lebanon's state news agency on Sunday reported a series of overnight Israeli airstrikes on Beirut's southern suburbs, after Israel's army issued fresh evacuation calls.

The official National News Agency said shortly after midnight that Israel had "targeted the southern suburbs of Beirut."

Iran warned it would defend itself after Israeli air strikes killed at least four soldiers and further stoked fears of a full-scale war in the Middle East.