BEIRUT — Syrian forces opened fire across two tense borders Monday, killing a TV journalist in Lebanon and wounding at least six people in a refugee camp in Turkey on the eve of a deadline for a cease-fire plan that seems all but certain to fail.
A witness at the Turkish camp said he saw two refugees killed, although that account could not be independently confirmed.
Across Syria, activists reported particularly heavy violence with more than 125 people killed in the past two days.
The Obama administration expressed outrage at the violence spilling over the frontiers, saying the Syrian government appeared to have little commitment to the peace plan that was negotiated by former U.N. chief Kofi Annan.
The latest bloodshed was a sign of how easily Syria's neighbors could be drawn into a regional conflagration as President Bashar Assad's crackdown on a year-old uprising becomes increasingly militarized, despite desperate diplomatic efforts.
Annan brokered a deal that was supposed to begin with Syria pulling its troops out of population centers by Tuesday morning, with a full cease-fire by both sides within 48 hours.
But hopes for the plan collapsed after a fresh wave of violence and new demands by the regime for written guarantees that the opposition will lay down arms first.
Naci Koru, Turkey's deputy foreign minister, said Tuesday's deadline for the withdrawal has become "void at this stage," state-run TRT television reported.
The U.N. estimates some 9,000 people have been killed in Syria since March 2011, when the uprising began with mostly peaceful protests against Assad. But a government crackdown led many Syrians take up weapons, transforming the conflict into an insurgency.
On Monday, Syrian forces fired across the border into a refugee camp in Turkey, wounding at least six people, authorities said.
The soldiers were believed to be firing at rebels who tried to escape to the refugee camp after ambushing a Syrian military checkpoint, killing six soldiers, according to the Britain-based activist group Syrian Observatory for Human Rights.
The troops kept firing as they pursued rebels who made a run for the camp, sending bullets whizzing across the frontier, the Observatory said.
Turkish authorities said four Syrians and two Turks were wounded, including a Turkish translator who had entered the camp to try to calm an anti-Assad protest.
But one witness, Tareq Abdul-Haqq, told The Associated Press by telephone from the camp that he saw two refugees killed in front of him.
He said the two were in a crowd that was shouting anti-Assad slogans during a demonstration that erupted after word got through the camp that rebels had ambushed the Syrian checkpoint.
"They started chanting 'God is Great!' and the army and the security forces targeted them," Abdul-Haqq, 26, told The Associated Press by telephone.
The Turkish Foreign Ministry also reported two deaths, but under different circumstances.
According to the ministry, 21 wounded Syrians were brought to Turkey on Monday, but that two of them died soon after. It was not immediately possible to reconcile the two accounts.
"Syrian citizens who have fled the violence by the current Syrian regime are under the full protection of Turkey," the Turkish Foreign Ministry said in a statement.
Turkey shelters some 24,000 Syrian refugees, including hundreds of army defectors, and has floated the idea of setting up a buffer zone inside Syria if the flow of displaced people across its border becomes overwhelming.