Updated 3:22 p.m. ET -- Turkey's military struck targets inside Syria on Wednesday in response to a mortar bomb fired from Syrian territory that killed five Turkish civilians, Prime Minister Tayyip Erdogan's office said in a statement.
"Our armed forces at the border region responded to this atrocious attack with artillery fire on points in Syria that were detected with radar, in line with the rules of engagement," the Turkish statement said.
"Turkey, acting within the rules of engagement and international laws, will never leave unreciprocated such provocations by the Syrian regime against our national security," it said.
Turkey's NTV television said Turkish radar pinpointed the positions from where the shells were fired on the southeastern Turkish town of Akcakale, and that those positions were hit.
"Turkey is a sovereign country. There was an attack on its territory. There must certainly be a response in international law. ... I hope this is Syria's last craziness. Syria will be called into account," said Turkish Deputy Prime Minister Bulent Arinc.
The mortar bomb fired from Syria landed in a residential district of Akcakale on Wednesday, killing a woman and four children from the same family and wounding at least eight other people.
A Reuters witness saw the seriously wounded people -- three of them police officers -- being taken to hospital after the explosions in the Sanliurfa province.
Turkish Foreign Minister Ahmet Davutoglu briefed the United Nations mediator on Syria, Lakhdar Brahimi, about the incident by telephone, the Turkish Foreign Ministry said in a statement.
NATO Secretary-General Anders Fogh Rasmussen told Davutoglu he strongly condemned the strike, a NATO spokeswoman said.
The spokeswoman said NATO continued to follow developments in the region "closely and with great concern."
Davutoglu earlier had contacted Rasmussen, who has said repeatedly that NATO has no intention of intervening in Syria but stood ready to defend NATO member Turkey, if necessary.
Television footage showed a cloud of smoke and dust rising up as residents ran to help the wounded.
"It (mortar round) hit right in the middle of the neighborhood. The wife and four children from the same family died," Ahmet Emin Meshurgul, local head of the Turkish Red Crescent, told Reuters, adding he knew the victims personally.
"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," he said.
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In Turkey, the state-owned Anadolu news agencyreported that there had been two explosions.
"Following the first blast, many homes and businesses were damaged. A second blast took place at the same location. According to preliminary reports, at least three people were killed and nine others wounded. Among the wounded were Turkish police officers," Ayhan told Anadolu.
The conflict in neighboring Syria has affected border areas in the past when stray bullets have flown into Turkish territory.
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A mortar bomb fired from Syria damaged homes and workplaces in Akcakale last Friday but there were no deaths.
Turkey beefed up its troop presence and air defenses along the border after Syria shot down a Turkish reconnaissance jet in June.
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In April, Turkey officially reported an incident to the United Nations 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 frontier.
"We are outraged that the Syrians have been shooting across the border. We are very regretful about the loss of life that has occurred on the Turkish side," Secretary of State Hillary Clinton said in remarks Wednesday during an appearance with Kazakhstan's visiting foreign minister.
"We are working with our Turkish friends. I will be speaking with the (Turkish) foreign minister later to discuss what the best way forward would be," Clinton said, calling the spread of violence beyond Syria's borders "a very, very dangerous situation."
Reuters contributed to this report.
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