- White Helmets are a group of volunteers who work to save lives in Syria
- Barrel bomb attacks more common as war in Syria drags on
The group tweeted that the center and vehicles at the scene were destroyed Wednesday, and some volunteers injured in the attack.
White Helmets members describe themselves as a group of 3,000 volunteers whose goal is to save lives in Syrian communities.
"We rush to the scene of attacks to save the greatest number of lives in the shortest possible time and to minimize further injury to people and damage to property," the group says on its website.
Barrel bomb attacks are becoming more common as the war in Syria drags on in its fifth year
The explosive-laden barrels are hurled out of helicopters.
When one strikes, it can produce the seismological equivalent of a 7.6 magnitude earthquake, the White Helmets' James LeMesurier told CNN's Chief Medical Correspondent Dr. Sanjay Gupta.
Some of the most most deadly attacks since the start of the war have targeted the rebel-held areas in the city of Aleppo.
Barrel bombs killed more than 3,000 civilians in Aleppo in 2014, according to a report by Amnesty International.
The human rights organization said barrel bombs are a common tactic of the Syrian government, which has been fighting rebels since the civil war started in 2011.