Palestinian medical officials say an Israeli strike on a home where displaced people were sheltering in the northern Gaza Strip has killed at least 19 people.

Iran’s Supreme Leader Ayatollah Ali Khamenei said the recent events in Syria, including the fall of its government, were part of a joint plan by the United States and Israel, state TV reported Wednesday.

“There should be no doubt that what has happened in Syria is the result of a joint American and Zionist plan," it quoted Khamenei as saying. “We have evidence, and this evidence leaves no room for doubt.”

Israel's Defense Minister Israel Katz said Tuesday that Israel's military destroyed Syria’s fleet overnight and intends to establish a demilitarized zone “in southern Syria” to prevent attacks on Israel.

He also issued a warning to Syria’s rebels, saying that “whoever follows Assad’s path will end up like Assad — we will not allow an extremist Islamic terrorist entity to act against Israel across its border while putting its citizens at risk.”

Eight people were killed and three more injured when a six-story residential building collapsed in central Cairo on Tuesday, Egypt's health ministry said.

They came from all over Syria, tens of thousands. The first place they rushed to after the fall of their longtime tormentor, former President Bashar Assad, was here: Saydnaya Prison, a place so notorious for its horrors it was long known as "the slaughterhouse."

For the past two days, all have been looking for signs of loved ones who disappeared years or even decades ago into the secretive, sprawling prison just outside Damascus.

Gaza's civil defense agency said Tuesday that Israeli strikes in the north of the Palestinian territory had killed 25 people, including women and children.

"At 8:00 PM last night, Israeli strikes targeted a multi-story building belonging to the Al-Kahlut family, killing 25 people. Sixteen bodies have been identified, while others remain trapped under the rubble," civil defense spokesman Mahmoud Bassal told AFP, adding five women and five children were among the dead. The Israeli army did not comment on the strike.

Turkey on Tuesday accused Israel of an "occupying mentality" after its forces entered a UN-patrolled buffer zone on the Golan Heights after the ouster of Syrian strongman Bashar al-Assad.

"We strongly condemn Israel's entry into the separation zone between Israel and Syria," a foreign ministry statement said, adding: "In this sensitive period.. Israel is once again displaying its occupying mentality."

For the first time in 50 years, the question of how Syria will be governed is wide open. The end of the Assad family's rule is for many Syrians a moment of mixed joy and fear, of the total unknown.

The insurgency that swept President Bashar Assad out of power is rooted in Islamist jihadi fighters. Its leader says he has renounced past ties to al-Qaida, and he has gone out of his way to assert a vision of creating a pluralistic Syria governed by civil institutions — not dictators and not ideology.

The dramatic downfall of Syrian President Bashar Assad presents possible danger, and an opening, for neighboring Israel.

After fighting wars on multiple fronts for months, Israel is now concerned that unrest in Syria could spill over into its territory. Israel also views the end of the Assad regime as a chance to disrupt Iran's ability to smuggle weapons through Syria to the Lebanese militant group Hezbollah.

The U.S. government's top hostage negotiator is in Beirut in hopes of collecting information on the whereabouts of Austin Tice, an American journalist missing in Syria for 12 years, the State Department said.

Roger Carstens, the special presidential envoy for hostage affairs, is talking to officials in the region following the overthrow of Bashar Assad's government to find out where Tice is and "get him home as soon as possible," State Department spokesman Matthew Miller told reporters Monday.