Eight people were killed in an explosion at a mosque of the Alawite minority sect in the Syrian city of Homs on Friday.
Syrian state news agency SANA cited health ministry official Najib al-Naasan as saying 18 others were wounded and that the figures were not final, indicating they could rise.
Homs city's press office said an explosive device had detonated inside the Imam Ali bin Abi Talib mosque and that security forces had cordoned off the area.
Local official Issam Naameh told Reuters the blast took place during Friday noon prayers, typically the busiest time for mosques.
There was no immediate claim of responsibility for the attack. Syria's foreign ministry condemned the blast as a "terrorist crime".
Syria has been rocked by several episodes of sectarian violence since longtime leader Bashar al-Assad, an Alawite, was ousted by a rebel offensive last year.
Earlier this month, two American soldiers and a civilian interpreter were killed in central Syria by an attacker described by the authorities as a suspected member of the IS.

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