Two of the dead are members of the Hamas resistance group, including senior official, Ghassan Abassi. The identity of the fourth Palestinian was not immediately known.
Our correspondent said the boy died in hospital. He also said 30 Palestinian men, under the age of 40, were detained by occupation force during raids on homes in the cities of Ram Allah and Bira and the districts of al-Tirah, Irsaal, Ram Allah al-Tahtah and Shurfah.
An Israeli army spokesman said troops killed two Palestinians during clashes near al-Amari refugee camp in the city and a third in another district while throwing grenades at them.
Israeli forces demolished two houses in Masyoun district and partially damaged a house in al-Amari refugee camp before withdrawing.
The military also claimed to have uncovered and destroyed an explosives laboratory.
Palestinian witnesses said soldiers also destroyed an internet café.
Palestinians are routinely held
The searches were an effort to find weapons used in anti-occupation attacks, the Israeli military said.
An Israeli official, speaking on condition of anonymity, denied the raid was timed to coincide with the signing of the Geneva Accord, which Prime Minister Ariel Sharon and Palestinian factions have called subversive.
Palestinian President Yasir Arafat has been confined to his headquarters in Ram Allah, but the raid did not cover that area of the city.