The blasts blew a crater in the street in Reyhanli on Turkey's border with Syria, The Wall Street Journal reported. The bombs detonated outside a municipal building and a school about noon.
Turkish officials suggested Syrian President Bashar Assad might be responsible. Foreign Minister Ahmet Davutoglu met with reporters during a trip to Berlin, the state-run Anadolu Agency said.
"Nobody should dare test Turkey's power and force. ... It is not a coincidence that these happen in a time when there has been acceleration in the Syria issue," Davutoglu said. "Our security forces will take all necessary measures."
Prime Minister Recep Tayyip Erdogan also suggested Assad might be retaliating for Turkey's assistance to Syrian rebels and its welcome to about 300,000 Syrian refugees.
A minibus exploded in February near Reyhanli, killing 14 people, most of them Syrian.