At least two blasts were reported near municipal offices in the town of Reyhanli in Hatay province,
The cause of the explosions is unknown. Thousands of refugees have fled Syria across the Reynhanli border.
Five people were killed last October when a mortar round hit the Turkish border town of Akcakale.
The mayor of Reyhanli Huseyin Sanverdi told Turkish media that a municipal building and a post office were hit.
Interior Minister Muammer Guler promised a government investigation.
The border area of Reyhanli has itself been attacked in recent months. In February, dozens of people were wounded when a mortar round landed close to a border gate.