The third explosion in the Turkish town of Reyhanli, close to the Syrian border, appears to have been a smaller blast caused by a car engine or a building boiler room, local reporters have told Reuters.
It followed two car bombs that exploded in the early afternoon in the city and killed around 40 people.
A third bomb has exploded in Reyhanli, a Turkish town near the border with Syria, according to AFP.
Syrian President Bashar al-Assad's government are the "usual suspects" behind car bombs in Turkey that killed around 40 people and wounded 100 more, Turkish deputy prime minister Bulent Arinc said.
He added that Turkey must wait for the results of an investigation before deciding on any response.
The blasts occurred in the town of Reyhanli close to the border and home to many of the more than 300,000 refugees who have sought shelter from the uprising against Assad that erupted in Syria in March 2011.
A Turkish minister said the death toll in the blasts near the border with Syria has risen to around 40, according to the Associated Press citing NTV television.
Eighteen people were killed and more than 20 injured in car bomb attacks in the Turkish town of Reyhanli near the Syrian border today, Turkey's interior minister was quoted as saying by domestic media.
The death toll from an explosion near Turkey's border with Syria has risen to 13, a Turkish official has said.
Officials have said the explosions close to the Syrian border in the Turkish town of Reyhanli, which have killed at least four people and left 18 injured, were caused by two car bombs.
Confirming the casualty figures, Turkey's interior minister Muammer Guler said: "Of course we are worried the numbers could rise".
He said the cars exploded in front of a municipality building and a post office.
At least four people have been killed and 18 injured in explosions near Turkey's border with Syria, the Turkish interior minister has said.
Four blasts occurred near municipal offices in the town of Reyhanli, in the southern province of Hatay, Turkey's Dogan news agency reported.