Israel-Gaza-Lebanon live updates: IDF investigates 'painful' Hezbollah drone strike

The Israel Defense Forces said Monday it killed a Hezbollah commander responsible for anti-tank missile forces.

The IDF said in a statement posted to social media that Muhammad Kamal Naim was killed in an airstrike in the Nabatieh region of southern Lebanon.

Naim, it said, was responsible for the elite Radwan Force's anti-tank weapons.

Naim "was responsible for planning and carrying out many terrorist plots, including firing anti-tank missiles at the Israeli rear," the IDF wrote.

At least 20 people were killed in an Israeli airstrike on a United Nations Relief and Works Agency for Palestine Refugees in the Near East school-turned-shelter in central Gaza, the Hamas-run Health Ministry in Gaza said.

The school was being used to shelter displaced people in Nuseirat camp, health authorities said. It was bombed on Sunday.

The school was earmarked for use in the planned second round of the Gaza polio vaccination campaign, which was due to begin on Monday.

-ABC News Diaa Ostaz and Guy Davies

Ten people were killed in shelling at an aid distribution center in the Jabalia camp in northern Gaza on Monday morning, according to the Hamas-run Health Ministry in the strip.

The area has been the focus of intense recent Israeli military activity, with the Israel Defense Forces reporting fierce fighting with Hamas militants there.

The IDF has ordered residents of northern Gaza -- of whom there are an estimated 200,000 to 400,000 -- to leave the region, which it has classified as a military zone.

Hamas is urging residents to stay, suggesting Israel will not allow those who leave to return.

Gaza's Civil Defense said there was a "complete siege" of Jabalia. Aid agencies have said that no food has been allowed to enter the north of Gaza since Oct. 1.

-ABC News' Nasser Atta and Guy Davies

Israeli Defense Minister Yoav Gallant visited the scene of a deadly Hezbollah drone strike in northern Israel on Monday, telling soldiers there the incident "was a difficult event with painful results."

Four troops were killed and 55 wounded in Sunday's attack on the Golani Training Base close to the town of Binyamina, some 20 miles south of Haifa.

"We must investigate it, study the details and implement lessons in a swift and professional manner," Gallant said, according to a Defense Ministry readout.

"We are concentrating significant efforts in developing solutions to address the threat of UAV attacks," he added

-ABC News' Jordana Miller