According to the Observatory, the shooting wounded five people in the camp, which is next to the Oncupinar border post near the town of Kilis in Gaziantep province. The Observatory reported that two people later died of their injuries, but that could not be immediately confirmed.
The province's governor, Yusuf Odabas, said five people were wounded: three Syrians, one Turkish translator and one Turkish policeman. The translator had entered the camp to try to help calm an anti-Assad protest, he said. The governor said Turkish military forces did not return fire.
The shooting prompted Ankara, which has been among Assad's harshest critics, to summon the Syrian charge d'affaires and call for an immediate halt to the gunfire.
Turkey hosts some 24,000 Syrian refugees, including hundreds of army defectors, and has floated the idea of setting up a buffer zone inside Syria if the flow of displaced people across its border becomes overwhelming.
The two countries share a 911-kilometer (566-mile) border, and parts of southern Turkey near Syria are informal logistics bases for rebels, who collect food and other supplies in Turkey and deliver them to comrades inside Syria via smuggling routes.
The Syrian uprising began last year with mostly peaceful protests against the Assad regime, a family dynasty that has ruled the country for four decades. But in the face of a relentless military assault on protests, the opposition has become increasingly militarized.
Now, the uprising resembles an armed insurgency, and there are fears the country is spiraling toward civil war. International envoy Kofi Annan brokered a cease-fire that was supposed to begin Tuesday, but the plan is in tatters.