Attempt to secure return of
Palestinian refugees in Syria fails

"Other reports indicate that the Assad regime attempted to recruit the PLO and viewed their announcement of neutrality as something of a betrayal, particularly in light of the assistance and aid Damascus has offered them in the past.
Over the past month, Palestinian refugees in Syria have found themselves in the firing line of both the Assad regime forces and certain Syrian opposition militias."
I think it is only the government that has been firing at them.