Rebels tore down a Syrian flag at a border gate on the Turkish frontier on Wednesday as they fought for control of the crossing, and schools on the Turkish side shut as bullets flew into Syria's northern neighbour.
Television footage showed Syrian rebels taking down the Syrian flag on top of a government building at the Tel Abyad border gate. Sporadic gunfire could be heard and black smoke rose from parts of what appeared to be a customs building.
Turkish officials were unable to confirm whether the rebels, fighting to overthrow Syrian President Bashar al-Assad, had seized control of the whole crossing, and said Assad's forces might send in reinforcements at any time.
There was no sign of any government troops at the crossing from television pictures broadcast live on CNN Turk.
The fighting, which started late on Tuesday, looked to be the first attempt by insurgents to assert their grip over a border zone in Syria's al-Raqqa province, most of which has remained solidly pro-Assad.
Rebels hold two other crossings on the northern border with Turkey. A third border point would strengthen their control in the north and put more pressure on Assad's army as the two sides battle for control of Syria's largest city Aleppo not far away.
The governor's office in the small town of Akcakale, on the Turkish side of the border post, ordered all schools in the town and the neighbouring villages to close for the day and banned all agricultural work in the area.
"A heavy hail of bullets is landing here. We are scared. We had to stay in another house last night. We don't know what to do," one man in his forties told CNN Turk television only metres from the fence separating both countries.
"Teachers, everyone have left the school next to us, they have fled the area," he said.
Syrian jets also bombed the Syrian town of Albu Kamal near the Iraqi border on Wednesday, Iraqi security officials and the mayor of Iraqi frontier town al-Qaim, said. The two towns are metres away from each other on the banks of the River Euphrates.
One Turkish woman and her daughter were wounded on Tuesday night by stray bullets and an official said other bullets had smashed windows in several houses along the border.
Ankara has yet to give a reaction to the fighting along its frontier but a similar incident earlier this year prompted a sharp rebuke from the government.
Turkey officially reported to the United Nations an incident in April in which at least five people, including two Turkish officials, were wounded when cross-border gunfire hit a Syrian refugee camp in Kilis further west along the border.
Turkish Prime Minister Tayyip Erdogan then floated the idea of invoking NATO's Article 5 over the incident saying the alliance had a duty to protect its members' borders.
Article 5 of the NATO treaty states an armed attack against one of its members will be considered an attack against all members and allows for the use of armed force. It has been invoked only once, following the Sept. 11, 2001, attacks on the United States.
Erdogan spoke to U.S. President Barack Obama late on Tuesday, his office said in a statement. The two leaders discussed the crisis in Syria among other issues. The statement made no reference to the border incident.
Once an ally of Assad, Erdogan is now among his most vocal critics and has called for him to step down. Turkey actively supports the rebellion against his government, giving fighters sanctuary on its soil and allowing opposition members to meet in Turkish cities.
It is also sheltering some 83,000 Syrians who have fled the violence in camps along the border.
The 18-month-old revolt, which began as peaceful street protests cracked down on by Assad's military, has escalated into a civil war in which over 27,000 people have died. Daily death tolls now approach 200 and the last month was the bloodiest yet.