A Syrian jet has bombed a rebel-held region near the border with Turkey for a second day, sending residents fleeing across the frontier.
Sources in the border town of Ras al-Ain told Al Jazeera that a military base and a civilian neighbourhood were hit on Tuesday.
Plumes of smoke could be seen from the Turkish town of Ceylanpinar, separated from Ras al-Ain only by a barbed wire fence.
An official in the mayor's office said the jet struck an area near the Turkish border "five times within a period of 10 minutes".
Turkish ambulances rushed to the border to pick up Syrians wounded in the attack. The official told the AP news agency that four injured Syrians were brought to Turkey for treatment and one of them died.
Syrian rebels wrested control of Ras al-Ain from government forces last week in fighting that sent 9,000 people fleeing in a 24-hour period. The exodus was one of a largest refugee influxes into Turkey of the 19-month conflict.
The town is located in the predominantly Kurdish oil-producing northeastern province of al-Hassake.
Ahmet Davutoglu, the Turkish foreign minister, said Turkey had formally protested to Damascus against bombings close to its border, saying the attacks were endangering Turkey's security.
Davutoglu said Turkey had also reported the incident to NATO allies and to the UN Security Council.
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Turkey is reluctant to be drawn into a regional conflict, but has responded with mortars after shells fired from Syria landed on Turkish territory.
About 120,000 Syrian refugees are living in camps in the border area.
Near the capital, Damascus, opposition activists said fierce clashes between government forces and rebels left 10 soldiers and a rebel dead on Tuesday.
The fighting in the Damascus suburb of Eastern Ghouta came after rebels launched an attack on public buildings in the area, the Britain-based Syrian Observatory for Human Rights said.
The opposition says more than 35,000 people have been killed since the Syrian uprising began in March last year. The conflict has become increasingly bloody, with rebels launching attacks against President Bashar al-Assad's forces.
Both opposition forces and the regime have been accused of abuses by human rights groups.
Assad has pledged to stay in power, blaming foreign countries of stoking conflict in his country.