A police officer has died and at least 10 other people have been injured after gunfire broke out on Syria's border with Turkey, officials say.
The violence started on Thursday as Syrians trying to cross into the neighbouring country opened fire across the border towards the Turkish guards.
An entry post was also set on fire during the clash.
Abdulhakim Ayhan, mayor of the border town of Akcakale, said shots were fired when Turkish authorities issued warnings to a large group of Syrians trying to cross illegally.
There were conflicting reports as to the identity of the group, with some describing them as smugglers while others said they were civilians trying to escape the violence. Another report said the group had included Syrian rebels.
A police officer died in hospital while six more were injured. Up to five civilians were also wounded during the violence.
Al Jazeera's Hashem Ahelbarra, reporting from Turkey, said violence on the border was becoming an increasing source of concern for Turkey.
"Turkey was not expecting the conflict to drag on this long and it is now bracing itself for the potential disastrous fallout," he said.
"They have to consider the mass exodus of refugees, the potential use of chemical weapons, and the growing rise of radical groups inside Syria."
Our correspondent also said that Turkey's open support for the predominantly Sunni rebels created concerns about the possibility of sectarian violence within Turkey.
Ahelbarra said the upcoming meeting between Turkish Prime Minister Recep Tayyip Erdogan and US President Barack Obama would contain a very clear message that the US needs to take control of the violence before the fighting spills over into the rest of the region.
Elsewhere in Syria, there were reports of a "massacre" in which dozens people are thought to be dead.
The Syrian Observatory for Human Rights said state forces loyal to Bashar al-Assad entered the coastal village of Baida on Thursday and killed people including women and children.
Due to reporting restrictions in Syria, Al Jazeera is unable to independently verify these claims.
Meanwhile, Syrian government troops on Thursday pushed into the central districts of the city of Homs in an effort to oust rebels from the country's third largest urban centre, the Observatory said.
It said the regime's manoeuvres in the area killed seven people, including four children.
President Bashar al-Assad's troops regained control of the Wadi Sayeh district in the centre of Homs early on Thursday morning, the Observatory said.
"Taking Wadi al-Sayeh would enable the army to isolate those two districts" by severing links between them, said the Britain-based group.