A Syrian monitor says Islamic State militants have launched an attack on government-held areas of the Syrian city of Deir el-Zour.
The British-based Syrian Observatory for Human Rights reports several explosions rocked the eastern city in the intense offensive.
Officials say the Syrian government used warplanes to beat back the militants.
Unconfirmed reports say dozens of people have been killed.
The Islamic State group controls most of Deir el-Zour province, but government forces have maintained control of the provincial capital.