JERUSALEM - Israel was releasing about 550 Palestinian prisoners Sunday in the second half of a swap that freed one of its soldiers, Sgt. Gilad Shalit, who had been held by Hamas in Gaza for more than five years.

The prisoners had been gathered at several spots and were being sent by bus, most of them to the West Bank, with a small group going to Gaza and a few to East Jerusalem and Jordan.

The first phase of the exchange took place in October and involved hundreds of Palestinians serving life sentences, many of them Hamas members convicted of killing Israelis. There are no members of Hamas or Islamic Jihad in the second group.

About half the prisoners were serving four years or less, and a third two years or less, often for acts such as throwing stones or Molotov cocktails or possessing weapons. About 10 percent had sentences of 10 years or more, mostly for throwing or planting bombs or attempted murder. Ten percent are younger than 18 years old; three of the prisoners are 14 years old.

Palestinians expressed anger that the release was taking place at night, making it difficult to celebrate, and said that those being freed were not the ones they would have chosen first.

"This is not a serious part of the exchange," Issa Qaraqe, the minister of detainees for the West Bank-based Palestinian Authority, said by telephone. "Many of those being released were due to get out within months anyway and there are women left behind and prisoners who have been there a long time."

Palestinian youths threw stones at Israeli troops near Ramallah in the West Bank as the release got under way. The soldiers responded with tear gas and rubber bullets. There were more than a dozen injuries reported among the Palestinians, and one soldier hurt.

Palestinian Authority President Mahmoud Abbas left Sunday for a visit to Turkey, so the reception planned for the released prisoners at the presidential compound in Ramallah was to be brief.

Shalit, who was 19 when he was abducted while on active duty near the Gaza border in 2006, emerged rail-thin and pale in the first phase of this exchange. He is at home with his family in northern Israel and undergoing occupational therapy and debriefing by the military, according to Israeli media reports. He has not yet spoken publicly of his years in captivity.