A bomb has exploded on the third floor of the Syrian state TV and radio building in the capital, Damascus, Syrian television reports.
Three people have been wounded, the reports say.
State TV continued broadcasting and pro-government TV channel al-Ikhbariya showed pictures of staff looking after an injured colleague.
In June, gunmen attacked the offices of al-Ikhbariya TV, south of Damascus, killing seven people.
Rebel forces took over several areas of Damascus in recent weeks, but the army has since regained control of the city.