Turkish artillery has fired on positions inside Syria after shells from Syria killed five people in a southern Turkish border town.
A woman and her three children were among those killed earlier when the shells, apparently fired by Syrian government forces, hit Akcakale.
Turkey’s response marks the first time it has fired into Syria during the 18-month-long uprising against Syrian President Bashar al-Assad.
Nato ambassadors discussed the crisis.
The military alliance issued a statement saying it “continues to stand by (Nato member) Turkey and demands the immediate cessation of such aggressive acts against an ally, and urges the Syrian regime to put an end to flagrant violations of international law”.
Turkey’s territory has been hit by fire from Syria on several occasions since the uprising against President Assad began, but Wednesday’s incident was the most serious.