US-led coalition aircraft were responsible for the air strikes which destroyed the Red Crescent's headquarters in Syria's Idlib, in what was a violation of international humanitarian law, President of Turkish Red Crescent Kerem Kinik said on Wednesday.
Earlier in the day, local media reported that airstrikes hit the Red Crescent headquarters in Idlib at around 3:00 a.m. (01:00 GMT), destroying the building's upper floors and injuring volunteers.
"We strongly condemn hideous air attack led by US coalition on #Idlib #RedCrescent HQ. It's clear #warcrime and #IHL violation," Kinik wrote on Twitter.
Idlib's medical facilities have previously been targeted by strikes, with a maternity hospital suffering shelling and a hospital supported by the Doctors Without Borders (MSF) destroyed last summer.
Syria has been in a state of civil war since 2011.