A fragile truce in Gaza has been shaken after a Palestinian schoolgirl was shot dead in a playground, and Hamas fired mortars at Israeli targets.
Classmates placed a plastic bouquet on Nuran's empty desk
Ten-year-old Nuran Deeb was hit in the head inside a United Nations-run school in Rafah, UN officials said.
Witnesses blamed Israeli troops, but Israel said an initial investigation suggested they were not responsible.
Despite the tensions, talks between the two sides on an Israeli pullback from West Bank towns went ahead as planned.
Palestinian officials said Nuran was struck in the head as she was walking inside the school in the Brazil neighbourhood of the Rafah refugee camp.
"She suddenly screamed and fell to the ground, bleeding. The girls started to run everywhere," one witness said.
Another girl was wounded in the hand.
The Israeli military said an investigation into the shooting found its troops had not opened fire in that area.
A military official, who wished to remain anonymous, said Palestinians nearby had been shooting into the air to celebrate their return from the Hajj pilgrimage to Mecca.
Palestinian residents said no such celebrations had taken place.
The Palestinian militant group Hamas fired six mortar shells in retaliation for the incident, damaging a house in an Israeli settlement.
It said the future of its informal ceasefire would depend on actions by the Israeli military.
The dead girl's mother told journalists: "We heard talk about a ceasefire. But it seems there is nothing like that on the ground.
"My daughter was lovely. Today she went to school earlier than usual. She said she wanted to play with her schoolmates before class."
The death is the second fatality in the area in two days. Israeli troops shot and killed a 65-year-old man who was walking near an army post on Sunday.
The Palestinian police have recently deployed throughout Rafah
Last week Palestinian leader Mahmoud Abbas won a commitment from militant groups to stop anti-Israeli attacks and thousands of officers were deployed throughout Gaza, including the flashpoint town of Rafah.
Although no formal ceasefire has been agreed, Israel has also scaled back its military operations in return.
Israeli Defence Minister Shaul Mofaz and Palestinian negotiator Mohammed Dahlan met on Monday night to discuss the details of a security handover in the West Bank.
Palestinian officials say they are expecting to take control of Ramallah, Qalqiliya, Tulkarem and Jericho this week.
Israel captured the West Bank and the Gaza Strip - home to about four million Palestinians - during the 1967 Six Day war.