Israeli soldiers chasing rock throwers opened fire at an uninvolved Palestinian car early Tuesday, killing a 15-year-old boy and injuring four others, officials said.An Israeli military spokeswoman in Tel Aviv admitted that the injured Palestinians were innocent passers-by mistakenly targeted by soldiers who believed they were chasing another group of Palestinians involved in a rock and firebomb attack on Israeli motorists.Palestine Liberation Organization Secretary General Saeb Erekat condemned the shooting as a "cold-blooded assassination" and said the United Nations should immediately investigate Israeli "extra-judicial killings" of Palestinians, particularly children.Erekat said that Mahmoud Badran, 15, from a village west of Ramallah, and the other passengers had been on their way home from a nearby swimming pool when their car suddenly came under fire.Three 16-year-olds and a 17-year-old were injured.The Israeli military said that three civilians were injured in the massive stone-throwing attack on a Jerusalem road that partly passes through the West Bank.Witnesses said a dozen cars were damaged in the incident."Nearby forces acted in order to protect additional passing vehicles from immediate danger and fired towards suspects," the military spokeswoman said, adding: "It appears that uninvolved bystanders were mistakenly hit during the pursuit."She said the Israeli army was investigating the incident.Top PLO official Hanan Ashrawi accused Israel of implementing a "shoot-to-kill" policy.The Palestinian Foreign Ministry also condemned the shooting, calling it a deliberate "field execution," and said it brought to 220 the number of Palestinians killed in a wave of violence since October.The ministry said the shooting came at a time when the "extreme-right government" of Israeli Prime Minister Benjamin Netanyahu was rejecting and foiling all international efforts to revive a "serious and genuine peace process," including a French initiative.