BEIRUT (AP) — Turkish artillery fired on Syrian targets Wednesday after shelling from Syria struck a border village in Turkey, killing five civilians, sharply escalating tensions between the two neighbors and prompting NATO to convene an emergency meeting.

"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 government said in a statement from the prime minister's office.

The artillery fire capped a day that began with four bombs tearing through a government-held district in Syria's commercial and cultural capital of Aleppo, killing more than 30 people and reducing buildings to rubble.