A Palestinian man died late on Wednesday hours after he was wounded by gunfire from a Gaza Jewish settlement.
It was the first conflict-related fatality since Israelis and Palestinians declared a truce on Tuesday, medics said.
The 20-year-old from a Rafah refugee camp in southern Gaza was shot from the nearby illegal settlement of Atzmona, which has an Israeli army garrison.
An Israeli military source said troops had fired warning shots, suspecting an infiltration attempt.
Settlers vow fight
Earlier, Jewish settler activists said they had obtained the signatures of 10,000 Israeli reservists vowing to disobey orders to carry out a planned Gaza withdrawal.
The petition came as Jewish settlers escalated efforts to derail Israeli Prime Minister Ariel Sharon's plan to remove all settlements from occupied Gaza and four in the West Bank, land they see as a biblical birthright.
"If, heaven forbid, this destructive order is issued, then the Defence Ministry should know that tens of thousands of soldiers would not come," Noam Livnat, a Jewish settler, said as he showed reporters a notebook filled with signatures.
Livnat is the brother of Education Minister Limor Livnat, who belongs to Sharon's Likud Party.