UN report shows army used chemical weapons on a hospital

"UN Mission also finds that, on the same day, the army directly and intentionally attacked the Al Quds Hospital and the adjacent ambulance depot with white phosphorous shells."

Report of the United Nations Fact Finding Mission 15 September 2009 para 35:



That site seems to be down a lot  here is a similar Guardian report:
Human Rights Watch report claims war crimes committed in use of air-burst white phosphorus artillery shells