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 opposition fighters 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.
The Turkish foreign ministry summoned the Syrian charge d’affaires in Ankara earlier on Monday to deliver a note of protest regarding the killings. The last incident happened in February when bullets struck a solar heating system mounted on a village house in Güveççi village at the Turkish-Syrian border with no reported injuries.
The statement strongly condemned the attack which it said took place at a time when Syrian troops should have been pulled out from cities according to Annan’s ceasefire plan.
Turkey warned Syria against repeating similar incidents again and said it is natural that Turkey will take necessary measures in that regard.
The statement called on Syrian regime to immediately halt violence against civilian people and urged the international community to act to make this happen.
The violence bolstered fears that the uprising could spark a broader regional conflagration by sucking in neighboring countries.
Under the Annan plan, 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.
According to the Syrian Observatory for Human Rights, the fighting along the Turkish border began before dawn on Monday when opposition 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.
According to the Observatory, the shooting wounded five people in the camp, which is next to the Öncüpınar border post near the provincial center of Kilis.
The provincial governor, Yusuf Odabaş, 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 quite and clashes are over," Odabaş said late Monday afternoon.
Turkey shelters thousands of refugees who have fled Syria as Assad tries to crush a revolt against his regime. The UN estimates some 9,000 people have been killed in Syria since March 2011, when the uprising began.
Turkey hosts more than 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 911-kilometer (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.
UN Secretary-General Ban Ki-moon said on Monday he deplores the cross-border shootings from Syria into Turkey and Lebanon ahead of the ceasefire deadline on Tuesday.
"The secretary-general is alarmed by the reports of continued violence and human rights violations in Syria, which resulted in an increased flow of refugees into neighboring countries," Ban's office said in a statement.
"The secretary-general strongly deplores today's fatal cross-border shootings from Syria into Turkey, as well as into Lebanon," it said.
The Obama administration also condemned the cross-border attacks.
“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," State Department spokeswoman Victoria Nuland told reporters in Washington. "Not only has the violence not abated, it has been worse in recent days," she said.