Ankara - At least 20 people were killed on Monday in an explosion in a cultural centre in the Turkish town of Suruc near the border with Syria, local television reported.
The cause of the blast in the town, which lies opposite the Syrian flashpoint of Kobane was not immediately clear.
But officials said it might have been a suicide bomb, and some commentators said it could have been the work of ISIS militants.
Several Turkish media reported fatalities and private television station NTV said at least 20 people had been killed and about 100 wounded.
Witnesses said fire broke out after the strong explosion which smashed the windows of the building.
Television footage showed several people lying on the ground covered in blood and ambulances rushing to the scene.
The blast came as Turkey was stepping up its role in the fight against the ISIS.
Arrests of ISIS militants
Last week, security forces arrested dozens of militants and sympathisers in the most significant action by Ankara against the jihadists who have seized swathes of neighbouring Iraq and Syria since 2014.
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A Turkish government official confirmed to AFP that the explosion occurred in the garden of a culture centre in Suruc.
But he declined to provide any casualty figures.
The blast took place as a group from Turkish left-wing youth associations were preparing to make a press statement Suruc to announce they would cross into Kobane.
The group was staying at the cultural centre.
Suruc, once a centre of silk-making, is now home to one of the biggest refugee camps in Turkey housing Syrians who have fled the bloody four-year conflict at home.
The camp, which opened in January, shelters about 35 000 refugees who crossed the border after Islamic State jihadists seized Kobane last year.
In January, Kurdish forces backed by rebel groups and US-led air strikes had pushed ISIS out of Kobane after four months of fierce fighting in a hugely symbolic defeat for the jihadists.
The Islamists make a surprise raid on the town in June but the fighters were driven back by Kurdish forces who took full control of the town.
But ISIS launched a surprise attack on the Syrian town last month, staging three suicide bombings and re-entering the town.
Many of the injured had been taken to hospitals in Suruc.
Several hundred thousand Syrians have taken refuge in Turkish camps along the border but the vast majority of them are scattered in major cities, where their presence has stoked tensions with locals.
Turkey has long been under international pressure to tighten the security of its volatile 911km border with Syria to cut the flow of jihadists who try to join the ranks of the Islamic State militants.
Ankara has always vehemently denied claims of Turkish collusion with ISIS and in turn accused the West of not doing enough to help with the burden of Syrian refugees, 1.8 million of whom are living in Turkey