Israeli troops have shot and critically wounded an 11-year-old Palestinian girl standing outside her school in Gaza.
Schoolchildren have frequently been caught up in violence
Ghadir Mokheimer was hit in the chest when troops opened fire towards the school. The Israelis said they returned fire after coming under mortar attack.
A schoolgirl from the same refugee camp in Khan Younis died last month after being shot in the head at her desk.
Israel has been hit by controversy over the death of another Palestinian girl shot by troops in Rafah last week.
The UN agency for Palestinian refugees (Unrwa) says the shooting is the fourth such incident in less than two years.
An Unrwa statement said it had "repeatedly called on the Israeli authorities to stop firing at schools".
However, it says Israel routinely denies its soldiers have been involved or invokes the security requirements of its positions.
"Peter Hansen, Unrwa's Commissioner-General has demanded that such shootings must stop," the statement says.
Israel radio reported that the army was investigating the incident, but a military spokesperson said initial checks indicated that troops opened fire at Palestinians in the area who were firing mortar shells at an Israeli settlement.
Israel has occupied the Gaza Strip since capturing it in the 1967 war.
The Israeli government intends to begin evacuating the 8,000 Jewish settlers and the troops who protect them in Gaza next year as part of a disengagement plan to enhance Israeli security.
Israel's military commander for the Gaza Strip is investigating the death of 13-year-old Iman al-Hams who was gunned down near the Girit army outpost in the Tel Sultan neighbourhood.
Preliminary inquiries have revealed "contradictions" between the officer's version of events and that of his men, Haaretz website reports.
The soldiers complained that after the first shots were fired at the girl, the company commander approached her motionless body, fired two shots to her head, and then sprayed her with automatic fire. The commander denies some of the accusations, Haaretz reports.
Relatives of Iman al-Hams have called her death a crime of hate
The case has been widely reported in the international media.
Huweida al-Hams, Iman's mother, described the incident as a "criminal act of hate" in an interview on Monday and called for God's punishment on the Israeli army.
The army has alleged Iman had been sent to the outpost by Palestinian militants planning to target the soldiers with snipers.
Initially, it said the troops suspected the girl of carrying a bomb in what later turned out to be her school satchel.