Syrian border violence kills Al Jadeed journalist Ali Shaaban in Lebanon, wounds refugees in Turkey

Updated at 3:59 p.m. ET

(CBS/AP) KILIS, Turkey - The bloody conflict in Syria spilled across two tense borders Monday when gunfire from government forces killed a cameraman in Lebanon and wounded at least six people in a refugee camp in Turkey, authorities said.

The violence came as a U.N.-brokered truce plan set to take effect on Tuesday all but collapsed, bolstering fears that the uprising could spark a broader conflagration by sucking in neighboring countries.

International envoy Kofi Annan brokered a cease-fire, but the plan is in tatters. Syrian troops were meant to pull out of population centers by Tuesday morning, but President Bashar Assad's government on Sunday introduced a new, last-minute demand — saying forces cannot withdraw without written guarantees from opposition fighters that they will lay down their arms.

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Syria's main rebel group, the Free Syrian Army, rejected the government's demand for a written guarantee, but says it will abide by its promise under Annan's plan to stop fighting — as long as the regime does too.

"We as protectors of the Syrian people announce a cease-fire against the regime's army starting on the morning of April 10 and we will stick to this promise if the regime abides by the clauses of the initiative," a member of the FSA's military council said in a YouTube video.

The Syrian opposition and Western leaders had been skeptical all along that Assad would live up to his commitment to a truce because he broke similar promises in the past and escalated attacks on opposition strongholds in the days leading up to the cease-fire deadline.

In Washington, State Department spokeswoman Victoria Nuland said the United States "strongly" condemned the attacks, CBS Radio News correspondent Cami McCormick reports.

"These incidents are just another indication that the Assad regime does not seem at all willing to meet the commitments that it made to Kofi Annan," Nuland said.

"Not only has the violence not abated, it has been worse in recent days," she said.

The U.S. wasn't optimistic that Assad would meet Tuesday's deadline, Nuland said, "but we're going to wait for tomorrow's deadline and take it from there."

In New York, U.N. Secretary-General Ban Ki-moon deplored Monday's shootings, his spokesperson said in a statement, CBS News foreign affairs analyst Pamela Falk reports.

In the latest violence, Ali Shaaban, a cameraman for the Al Jadeed television station, was filming in Lebanon's northern Wadi Khaled area when a bullet pierced his chest, Lebanese security officials said. The gunfire came from the nearby Syrian village of Armouta, the officials said.

Shaaban, who was born in 1980, died on the way to the hospital, the officials said on condition of anonymity in line with regulations.

His colleague, reporter Hussein Khreis, said the team heard heavy gunfire around them from all sides "falling like rain." Shaaban was inside a car when he was struck, Khreis said.

"If you see the car, you would think it was in a war zone," Khreis said on Al Jadeed TV. "It is completely destroyed from the bullets."

He said they waited for more than two hours for the Lebanese army and some residents to come and pull them out to safety.

"I ask forgiveness from Ali's family because I couldn't do anything for him," he said, breaking into tears.

Al Jadeed said that Syrian security officials dressed in civilian clothes fired more than 40 bullets at their staff, who were on Lebanese soil. Al Jadeed said on its Arabic Twitter account that the Lebanese military retrieved Shaaban's body from near the border.

The post on Twitter quoted a staff member as saying they had received threats from members of the Syrian army who were armed and dressed in civilian clothes.

Earlier in the day, Syrian forces fired across the border into a refugee camp in Turkey, wounding at least five people, authorities said. The soldiers were apparently firing at rebels who tried to escape to the refugee camp after ambushing a military checkpoint, according to the Britain-based activist group Syrian Observatory for Human Rights, which cited a network of sources on the ground.

Turkey's Foreign Ministry said two Syrian citizens and two Turkish officials were wounded when the camp came under fire from the Syrian side. Local authorities, however, put the number of wounded at four Syrians and two Turks. The reason for the discrepancy was not immediately clear.

"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.

It said 21 wounded Syrians were also brought to Turkey on Monday but that two of them died soon after.

According to the Syrian Observatory for Human Rights, the fighting along the Turkish border began before dawn Monday when rebel fighters attacked Syrian soldiers manning a checkpoint near the Turkish border, killing six soldiers.

Rami Abdul-Rahman, a spokesman for the Observatory, said the troops then kept firing as they pursued eight wounded rebels who escaped to the camp just across the border in Turkey, sending bullets whizzing across the frontier.

The provincial governor, Yusuf Odabas, said five people were wounded: three Syrians, one Turkish translator and one Turkish policeman. The translator had entered the camp to try to help calm an anti-Assad protest, he said.

The governor said Turkish military forces did not return fire.

"Right now, the border area is quiet and clashes are over," Odabas said late Monday afternoon.

Turkey shelters thousands of refugees who have fled Syria as Assad tries to crush a revolt against his regime. The U.N. estimates some 9,000 people have been killed in Syria since March 2011, when the uprising began.

Turkey hosts 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.

The two countries share a 566-mile border, and parts of southern Turkey near Syria are informal logistics bases for rebels, who collect food and other supplies in Turkey and smuggle them to comrades across the border.

Annan is scheduled to visit at least one refugee camp in Hatay province, bordering Syria, on Tuesday afternoon, Turkey's Foreign Ministry said.

Annan has been on a diplomatic push to rally support for his cease-fire deal. The international community, which so far is unwilling to contemplate military intervention, has had little leverage over Syria.

But Iran, Russia and China have been Assad's strongest supporters. Annan already has traveled to Moscow and Beijing, and he was expected in Tehran on Tuesday.

On Monday, Russia was hosting Syrian Foreign Minister Walid Moallem.

It is not clear whether Moscow will try to pressure Syria to comply with the cease-fire plan, though Russia said Monday it may send its observers to Syria as part of a potential U.N. monitoring mission.

Also Monday, Human Rights Watch said it has documented the killings by Syrian forces of 85 civilians, including women and children, and the summary executions of at least 16 wounded or captured opposition fighters.

The New York-based group said it only included cases corroborated by witnesses, but has received many more reports of similar incidents.