The IDF said it detained a Syrian citizen it alleged was working for Iran.
The Israel Defense Forces conducted what it called "precise strikes on military targets" in Iran on Friday in response to the Iranian missile strikes earlier this month.
Meanwhile, Israeli airstrikes and ground fighting continued in Gaza -- particularly in the north of the strip -- and in Lebanon, with renewed Israeli attacks on Beirut.
The second phase of the polio vaccination campaign has been unable to take place in northern Gaza City and the northern Gaza Strip, Director General of Field Hospitals in Gaza Marwan Al-Hams said Tuesday.
"About 110,000 children in northern Gaza need the second dose of the polio vaccine," Al-Hams said.
-ABC News' Sami Zyara
Israel will hit Iran harder if it launches more missiles, Israel Defense Forces chief Lt. Gen. Herzi Halevi warned Tuesday.
"If Iran makes the mistake of launching another missile barrage at Israel, we will once again know how to reach Iran, with capabilities that we did not even use this time," Halevi said, speaking at the Ramon Airbase.
At least 110 people were killed with more still missing following Israeli strikes on a five-story building housing displaced families in north Gaza on Tuesday, according to the Hamas-run Gaza Health Ministry.
At least 25 children were among the dead and missing, health officials said.
Local journalists reported that the strike hit a residential building in Beit Lahia in northern Gaza on Tuesday morning.
The only hospital still functioning in the area is Kamal Adwan Hospital, which in recent days has been the focus of Israeli strikes and raids.
Health officials said there are now no doctors capable of performing surgery left at the facility, dozens of medical staff having been detained by the Israel Defense Forces.
The IDF is yet to comment on Tuesday morning's strike.
-ABC News' Guy Davies and Joe Simonetti
The United Nations World Food Program issued a warning that the humanitarian crisis in Gaza could soon become a famine unless action is taken.
"Restrictions on humanitarian aid coming into Gaza are severe. During the month of October, only 5,000 metric tons of food have been delivered into Gaza, amounting to just 20 percent of basic food assistance for the 1.1 million people who depend on WFP’s lifesaving support," the WFP said in a statement.
"Meanwhile, Gaza’s food systems have largely collapsed due to the destruction of factories, croplands and shops. Markets are nearly empty as most commercial channels are no longer functioning," WFP said.
The WFP warned that a large group of Gazans could soon be in an "emergency phase" of need, while others would face "catastrophic" levels of food insecurity.
