Eight workers of the Syria Civil Defence, a rescue group that is also known as the White Helmets, died on Saturday after airstrikes hit their head office in the northern Hama province in the war-torn country, Reuters reported. The White Helmets, which announced the casualties on Twitter, operates in those parts of Syria which are held by the rebels.

The civil defence centre was located in Kafr Zeita, a town in the rebel-held northern Hama, which came under intense aerial bombardment on Saturday, the Syrian Observatory for Human Rights war monitor said. Civilians who rushed to the scene to help were also struck, reported Al Jazeera. The Britain-based monitoring group said the toll in the incident was likely to rise as the search mission continued.

It is not clear who carried out the airstrikes but the Syrian government led by Bashar al-Assad and Russia have frequently targeted rebel-held areas. The central Hama province has been the scene of intense violence in recent weeks, as the government attempts to push back a rebel offensive.