BENGHAZI, Libya (REUTERS) - Seven people were shot dead on Friday at a protest against Islamic State in the eastern Libyan city of Derna, residents said.

The protesters were marching towards the militant group's main base in Derna when gunmen there opened fire into the crowd, several residents said.

About 30 people were wounded, they added.

Nine suspected Islamic State in Iraq and Syria (ISIS) members were killed during separate clashes with other Islamist groups in the coastal city on Friday, a source in one of the groups opposing Islamic State said.

Islamic State and other Islamist militant groups have thrived in Libya since two rival governments began fighting for control, leaving a security vacuum four years after the overthrow of Muammar Gaddafi.

The rapid rise in Libya of ISIS, which first emerged in Syria and Iraq, is worrying Western powers who fear the militant group will forge a base just across the Mediterranean from mainland Europe.

Neither Libyan government has any control of Derna.