Air strikes have killed at least eight first responders from the Syria Civil Defense in Hama province, according to the group also known as The White Helmets.

Saturday's air strikes hit the rescuers' center in Kafr Zita, located in northwestern Syria. Civilians who rushed to the scene to help were also struck, according to the Syria Civil Defense’s Twitter posts.

The air strike was one of the deadliest against the rescuers who operate in opposition-held areas and who have grabbed world attention for operating in extreme conditions, pulling survivors out of recently struck areas.

The volunteers have often been targeted by regime air strikes, in what are known as "double tap" attacks, as they work to rescue others.

The Syrian Civil Defense operates in much of Syria's opposition-controlled territory.

The Syrian Observatory for Human Rights (SOHR), a Britain-based monitoring group, said the number of those killed is likely to rise as the search mission continues.

It was not clear who carried out the air strikes, but Syrian regime and Russian aircraft have targeted opposition-held areas.

Hama has been the scene of intense violence in recent weeks as the regime attempts to push back an opposition offensive.

PHOTO CAPTION

Members of the Civil Defense rescue children after an air strike by forces loyal to Bashar al-Assad in al-Shaar neighborhood of Aleppo, Syria June 2, 2014. REUTERS

Al-Jazeera