Israeli spy satellite plunges into the Mediterranean Sea. A11.
The Israeli military said the air force targeted the field, near the border with Israel, that was being used by Hamas for bomb assembly and training.
Angry Hamas militants gathered at Shifa Hospital in Gaza City -- some with blood on their clothes from carrying victims -- shouting ''revenge, revenge."
''This bloody crime is a new wave of aggression committed against our people and against our sons," Hamas spokesman Mushir al-Masri said. ''It's an ongoing war, one day for us and one day for them."
The Israeli statement listed activity that it said had taken place at the field in recent days, including the assembly of a large bomb and a suicide bomber's vest, practice in hijacking vehicles, and training in preparing and firing mortars and rockets.
Masri denied that the targeted field was used for training, calling it a summer camp for Palestinian youth.
Hospital officials said at least 13 people were killed and 25 wounded. Witnesses said the casualties were members of the Hamas military wing or supporters. Many wore military-style uniforms.
The airstrike was in the Shajaiyeh section of Gaza City, a known stronghold of Hamas. The casualty toll was the highest in Gaza City since May, when heavy fighting killed 31 Palestinians and 13 Israeli soldiers.
Yesterday, Israel's defense minister, Shaul Mofaz, said meanwhile that he is moving another planned section of the West Bank separation barrier closer to Israel. Israel says it needs the barrier to keep out suicide bombers.
The barrier is part of Prime Minister Ariel Sharon's contentious plan of ''unilateral disengagement" from the Palestinians, including a withdrawal from the Gaza Strip and the evacuation of four small West Bank settlements in 2005. Sharon has said he wants to keep several large West Bank settlements as part of any future peace deal.
One-third of the 425-mile barrier has already been built in the northern West Bank, but army planners have redrawn parts of the remaining route farther to the south to comply with the court order. Palestinians have contended that the wall's path in the north has cut them off from their land and other services.
