Thirteen people, including two police officers, were injured in the mortar attack on Akcakale, Turkish newspaper Hurriyet Daily News reported Wednesday.
Prime Minister Recep Tayyip Erdogan said in a written statement Wednesday Turkey had fired artillery at targets in Syria, The New York Times reported, citing the Anatolian News Agency.
"This atrocious attack was immediately responded to adequately by our armed forces in the border region, in accordance with rules of engagement," said the statement, issued by Erdogan's office.
"Turkey, in accordance with the rules of engagement and international law, will never leave such provocations by the Syrian regime against our national security unrequited."
Turkey contacted NATO and the United Nations before launching the artillery strike, the Times reported, noting the Turkish strike raised the question of whether NATO -- of which Turkey is a member -- would take a greater role in the conflict, and NATO called an urgent meeting on the development Wednesday.
U.S. Secretary of State Hillary Clinton said she was "outraged" by the mortar attack on Akcakale.
Residents of Akcakale protested the attack from Syria at the District Governor's Office in what Akcakale Mayor Abdulhakim Ayhan called an "uprising," infuriated by what they see as a spillover from the war in neighboring Syria, Today's Zaman reported.
"People here are anxious because we got hit before. Security forces tried to convince people to empty the neighborhood near the border, but now we've been hit right in the middle of the town," said Ahmet Emin Meshurgul, local head of the relief organization Turkish Red Crescent.
The report noted the mortar shells belonged to the Syrian army since rebels do not have such weapons.
U.N. Secretary-General Ban Ki-moon Wednesday urged Turkey 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," a U.N. spokesman said.
The spokesman said the secretary-general's admonition came during a call initiated by Foreign Minister Ahmet Davutoglu, with Ban expressing "his condolences at the 'tragic loss of life'" caused by the shelling.
More than 18,000 people, mostly civilians, have died since the uprising against the regime of Syrian President Bashar Assad began last year, the United Nations said. An estimated 2.5 million Syrians require humanitarian aid.
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