Interested in Turkey?Add Turkey as an interest to stay up to date on the latest Turkey news, video, and analysis from ABC News.
Turkish President Recep Tayyip Erdogan said the explosion appeared to be terror-linked.
The blast occurred inside a car some 750 meters (yards) from a local government office in the border town of Reyhanli, in Hatay province, Anadolu Agency said.
Earlier, Erdogan said three Syrians were killed in the explosion, but Interior Minister Suleyman Soylu later said only two were killed. The third Syrian was in serious condition.
Soylu said the explosion was caused by a hand-made bomb which went off while the car was in transit. He said all three Syrians were legally registered in Turkey. He did not identify them.
It is clear that there was a bomb inside the vehicle," Erdogan said. "The findings at the moment indicate that it was ... linked to terrorism."
In 2013, two car bomb attacks in Reyhanli killed 52 people, including Syrian refugees. Turkey blamed Syria's intelligence agency for the attack.
Turkey was also hit by a wave of attacks in 2015 and 2016 blamed on the Islamic State group and Kurdish militants that killed around 300 people.
In the last major attack, 39 people were killed when a gunman opened fire at an Istanbul nightclub during New Year celebrations in the early hours of 2017. The attack was claimed by the IS group.