Turkey protested angrily to the UN and NATO after Syrian shelling Wednesday killed five people in a town near the border.
The victims, among them a mother and her three children, were the first Turkish nationals killed by cross-border fire in the Syrian conflict.
Turkish Foreign Minister Ahmet Davutoglu called UN chief Ban Ki-moon, NATO chief Anders Fogh Rasmussen and the UN's Syria peace envoy Lakhdar Brahimi over the incident, his office said.
Davutoglu expressed Turkey's "deepest concern" to Ban, the UN chief's spokesman said.
Ban encouraged Davutoglu to "keep open all channels of communication with the Syrian authorities with a view to lessening any tension that could build up as a result of the incident," spokesman Martin Nesirky said.
Ankara also stressed that an attack on any NATO member is an attack against the entire alliance.
"The last incident went too far," Deputy Prime Minister Bulent Arinc was quoted as saying by Anatolia news agency.
"NATO treaty articles bring about certain liabilities when one of its members is attacked.
"We will not be blinded by rage, but we will protect our rights to the end in the face of an attack on our soil killing our people," he warned.
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The shells fired from Tall al-Abyad just across the border in Syria smashed into buildings in Akcakale, the second time that fire from Syria killed people inside Turkey since the uprising against the regime in Damascus erupted in March 2011.
In the previous attack in April, two Syrian nationals were killed on Turkish soil by stray bullets fired from the Syrian side.
"We lost five citizens," Akcakale mayor Abdulhakim Ayhan told Anatolia. "I offer my condolences to their families, and of course to all of Turkey."
The town of Akcakale has been fired on several times over the past few weeks.
Turkish officials have advised residents to stay away from the volatile border, and more than 100 schools have remained closed in the region over the past two weeks because of the violence.
On September 28, mortars smashed into buildings in Akcakale, wounding one person, with Turkey warning that it would respond if there was a repeat attack.
On Wednesday, the town mayor also said that "there is anger in our community against Syria," adding that stray bullets and shells had panicked residents for the past 10 days.
A week ago, the Turkish army deployed artillery and anti-aircraft missiles along the border in the region.
Since late July, Syrian rebels have seized control of at least three key border crossings with Turkey and others on the eastern border with Iraq.