BEIRUT — 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.

Along the volatile border, a shell fired from inside Syria landed on a home in the Turkish village of Akcakale, killing a woman, her three daughters and another woman, and wounding at least 10 others, according to Turkish media.

The shelling appeared to come from forces loyal to Syrian President Bashar Assad’s regime, which is fighting rebels backed by Turkey in an escalating civil war.

“Turkey, acting within the rules of engagement and international laws, will never leave unreciprocated such provocations by the Syrian regime against our national security,” the office of Prime Minister Recep Tayyip Erdogan said in a statement.

Turkish media said Turkey has prepared a parliamentary bill for Syria that is similar to one that authorizes the Turkish military to intervene in northern Iraq in pursuit of Kurdish militants who have bases there. The bill is expected to be discussed in parliament on Thursday, Anadolu agency reported.

If approved, the bill could more easily open the way to unilateral action by Turkey’s armed forces inside Syria, without the involvement of its Western and Arab allies.

Secretary of State Hillary Rodham Clinton said the U.S. was “outraged that the Syrians have been shooting across the border,” adding that she would speak with Turkish Foreign Minister Ahmet Davutoglu on the matter.

“It’s a very, very dangerous situation,” Clinton said. “And all responsible nations need to band together to persuade the Assad regime to have a cease-fire, quit assaulting their own people and begin the process of a political transition.”

NATO’s National Atlantic Council, which is composed of the alliance’s ambassadors, held an emergency meeting in Brussels Wednesday night at Turkey’s request to discuss the cross-border incident.

The meeting ended with a statement strongly condemning the attack and saying: “The alliance continues to stand by Turkey and demands the immediate cessation of such aggressive acts against an ally.” It also urged the Syrian regime to “put an end to flagrant violations of international law.”

NATO also held an emergency meeting when a Turkish jet was shot down by Syria in June, killing two pilots.

Turkey wants to avoid going into Syria on its own. It has been pushing for international intervention in the form of a safe zone, which would likely entail foreign security forces on the ground and a partial no-fly zone. However, the allies fear military intervention in Syria could ignite a wider conflict, and few observers expect robust action from the United States, which Turkey views as vital to any operation in Syria, ahead of the presidential election in November.