The injured were taken to Nasser Hospital in western Khan Younis, where the health ministry said it needed blood donations to help with treatment.
Medics told Reuters the tank salvo killed several people in the town of Bani Suhayla, more than a mile (about 2 kilometers) east of Khan Younis.
Unconfirmed reports quoted witnesses as saying tanks had entered Khan Younis.
Much of Gaza’s second-largest city was destroyed in an Israeli offensive that ended in April, but large numbers of people returned after troops began operations in nearby Rafah in early May.
They were again displaced earlier this month after the Israeli military issued new evacuation orders for other communities in eastern Khan Younis, as well as nearby towns and villages such as Bani Suhayra.
They were directed to the humanitarian zone – which stretches along the coast from Mawasi to the central town of Deir al-Balah – despite warnings from the United Nations that it was already crowded with tents and lacked basic services and critical infrastructure.
Mahmoud Abu Saqr, 46, told the BBC that he and his family fled Bani Suhaila on Monday and were now “sitting on the street” in the humanitarian zone.
“No one can buy a tent. Even if we have money, there is no way to build new tents here.
“Israeli artillery stationed at the border has been shelling our town since morning. In November we were displaced to Rafah and returned after the army asked us to return to the town. Today we received a text message on our mobile phones.
He added: “There is no such thing as a safe zone. It’s all lies.
The Israeli military said it was trying to “keep civilians away from fighting areas” and had adjusted the borders of the humanitarian zone “based on precise intelligence indicating that Hamas has buried terrorist infrastructure in the area.”
In response, Hamas called on the international community to “take urgent action to stop the series of systematic Zionist massacres against our people”.
On October 7, an unprecedented attack occurred in southern Israel, killing about 1,200 people and taking another 251 people hostage. Israel launched an operation to destroy Hamas in Gaza.
Since then, more than 39,000 people have been killed in Gaza, according to the region’s health ministry.
In another development on Monday, the Israeli military confirmed based on intelligence information that two more Israeli hostages had died in captivity.
An investigation into the circumstances of the death of 35-year-old Yagev Buchshtab is ongoing, a statement said. Alex Dancyg, 76, has Polish citizenship. Israeli media reports quoted military sources as saying it was “highly likely” that at least one of the men was killed by Israeli fire.
“Yagov and Alex were captured alive and deserved to be returned alive to their people and their country,” the Hostages and Missing Families Forum said in a statement. “Their deaths in captivity are a tragic reflection of the consequences of delays in negotiations. “
The forum demanded that Israeli Prime Minister Benjamin Netanyahu immediately ratify the ceasefire and hostage release agreement with Hamas.
Netanyahu’s office said on Sunday that he had held in-depth discussions with the Israeli negotiating team and directed them to participate in the next round of indirect talks brokered by Qatar and Egypt later this week.
Israel says 116 hostages remain in Gaza, 44 of whom are presumed dead. Four more hostages were kidnapped before 7 October. Two of them are believed to have died.
The Israeli military also said on Monday it was investigating a report that its troops opened fire on a marked United Nations convoy heading to Gaza City.
An armored vehicle was hit by at least five bullets on Sunday while waiting near an Israeli checkpoint south of the Gaza Valley, said Philippe Lazzarini, the head of the United Nations agency for Palestinian refugees (Unrwa). The vehicle was severely damaged and UN staff had to take shelter, but there were no casualties.
Lazzarini said the convoy’s actions had been coordinated with the Israeli authorities and demanded that “those responsible must be held accountable.”