At least 18 people have been killed and another 22 wounded in explosions in a Turkish town close to the Syrian border, officials say.
The blasts were reported in the town of Reyhanli in Hatay province, The interior minister told Turkish media they were caused by car bombs.
Thousands of refugees have fled Syria across the Reyhanli border.
Five people were killed last October when a mortar round hit the Turkish border town of Akcakale.
As many as four explosions were reported at around 13:45 local time (10:45 GMT), causing panic in the town, Turkish media said.
Reyhanli mayor Huseyin Sanverdi said a municipal building and a post office were hit. The municipal offices were badly damaged, reports said.
Local media reported that local people attacked cars with Syrian number-plates and Syrian refugees following the attack.
Interior Minister Muammer Guler promised a government investigation. He said there were fears the number of casualties could increase.
Meanwhile Foreign Minister Ahmet Davutoglu said Turkey would protect itself.
“No-one should attempt to test Turkey’s power. Our security forces will take all necessary measures,” Reuters news agency quoted him as saying in a visit to Berlin.
The border area of Reyhanli has itself been attacked in recent months. In February, 13 people were killed and more than 20 others wounded when a mortar round landed close to a border gate.
The Turkish government has been a key supporter of the Syrian opposition, and has allowed rebels as well as refugees onto its territory.
But tensions in the Reyhanli area have been high for several weeks, reports say, with clashes between Turkish and Syrian youths.