Israeli soldiers have shot dead two Palestinian teenagers in the West Bank, Palestinian security and hospital officials say.
The security officials said the pair, reportedly cousins, were among a group throwing stones at troops near the village of Beit Lakia, by Ramallah.
The soldiers were guarding the West Bank barrier Israel is building.
Israeli military officials said the troops fired warning shots in the air before shooting at the crowd.
The violence is likely to put further pressure on a truce declared by Palestinian President Mahmoud Abbas and Israeli Prime Minister Ariel Sharon at a February summit in Sharm el-Sheikh, Egypt.
"This is a violation of the ceasefire," Abbas aide Nabil Abu Rdainah told Reuters news agency.
"Israel is looking for excuses to raise tensions and to depart from implementing the Sharm understandings."
Israel says its West Bank barrier, a network of fortified fences and concrete walls, is a defence against Palestinian suicide bombers.
Palestinians say the barrier is a means of cementing Israel's hold on occupied Palestinian land.