A Hamas official in Lebanon claimed in an interview with Russian state media that the terrorist group planned Saturday's attack on Israel for two years.

The official, Ali Baraka, told the Russian state-controlled network RT in an interview posted earlier this week that Hamas prepared for the attack while Israel believed it was busy governing Gaza.

The State Department has raised its travel advisory level for Israel and the West Bank to "level 3 -- reconsider travel" due to terrorism and civil unrest.

"Terrorist groups, lone-actor terrorists and other violent extremists continue plotting possible attacks in Israel and the West Bank and Gaza," an alert from the department states. "Terrorists and violent extremists may attack with little or no warning, targeting tourist locations, transportation hubs, markets/shopping malls, and local government facilities."

Both regions were previously at "level 2 -- exercise increased caution."

The advisory also adds increased restrictions for U.S. government employees, declaring they can only travel to Israel for "mission-critical travel."

Gaza remains at "level 4 -- do not travel."

-ABC News' Shannon K. Crawford

President Joe Biden spoke with United Arab Emirates President Mohamed bin Zayed Wednesday to discuss the attacks in Israel, stressing his condemnation of Hamas’ brutality, according a White House readout of the call.

The two leaders also discussed ensuring humanitarian assistance for those in need and Biden's warnings against countries and organizations who may exploit the situation, according to the readout.

-ABC News' Justin Gomez

President Joe Biden said at a roundtable with Jewish leaders on Wednesday that the U.S. is "doing a lot" to rescue the Americans held hostage by Hamas.

"We're working on every aspect of the hostage crisis in Israel, including deploying experts to advise and assist with recovery efforts," he said. "I have not given up hope of bringing these folks home."

Second Gentleman Doug Emhoff also delivered remarks at the roundtable. Emhoff, the first Jewish spouse of a president or vice president, said, "Like all Jews, I feel a deep visceral connection to Israel and its people."

"We witnessed a mass murder of innocent civilians," he said. "The images that we saw will be seared in our brains forever. Rockets falling on cities, people dragged from their homes and shot dead, children sheltering from bullets, bodies lining the streets. And all the while, we see videos of these terrorists cheering on these atrocities. "

"I know you're all hurting. The entire Jewish community is hurting, I'm hurting," he said.

At least 500 people have been killed in an explosion at Al Ahli Arab Hospital in the middle of Gaza, according to the Gaza Health Ministry.

The hospital served as a shelter for thousands of residents who fled their homes in northern Gaza.

The Israel Defense Forces denied responsibility for the explosion, saying a failed launch by the Palestinian Islamic Jihad caused the blast.

"From the analysis of the operational systems of the IDF, an enemy rocket barrage was carried out towards Israel, which passed in the vicinity of the hospital, when it was hit," IDF said.

The World Health Organization condemned the blast and called for "the immediate active protection of civilians and health care" workers.

This hospital "was one of 20 in the north of the Gaza Strip facing evacuation orders from the Israeli military," the WHO said in a statement. "The order for evacuation has been impossible to carry out given the current insecurity, critical condition of many patients, and lack of ambulances, staff, health system bed capacity, and alternative shelter for those displaced."

Palestinian Authority President Mahmoud Abbas has declared three days of mourning following the attack.

-ABC News' Will Gretsky