Palestinian security forces said Israeli soldiers shot and killed Mujahid Samadi, a retarded 15-year-old Palestinian boy who was carrying a toy gun, on Wednesday.
Witnesses said the clashes had broken out when about 20 Israeli jeeps entered the village of Qabatiya, south of Jenin, in the early morning.
The victim had wandered out into the streets with a stick in his hand which the Israelis appeared to have mistaken for a weapon.
A spokesman for the army said that initial reports indicated that soldiers had identified a "suspect armed with a weapon who was threatening them and fired in his direction."
Palestinian security forces said Samadi died immediately after Israeli soldiers shot him through the chest.
The death brings the overall toll since the September 2000 start of the Palestinian uprising to 4955, according to an AFP count. The majority have been Palestinian.