>> Struggling to breathe using an oxygen mask to ease the pain. Just one of 33 victims of what's said to be a chemical attack in Syria, among them also women and children. Barrel bombs said to contain chlorine were dropped by a helicopter overnight on a rebel held area in Idlib province.
This video was posted online. Reuters correspondent Lisa Barrington in neighboring Lebanon says it's not uncommon.>> Syria Civil Defense told me that this was the second time that chlorine gas has been used in Saraqeb. In the Idlib province as a whole, they said since the beginning of the civil war about ten incidents have been brought to our attention.
It's very difficult to prove chemical attacks on both sides of accused, well all sides in the conflict have accused each other of using chemicals of various sorts.>> The attack came just hours after a Russian helicopter was shot down outside the same town. All five crew member on board were killed.
They'd reportedly been delivering aid to Aleppo where rebel forces have launched a major assault on government-held areas. The UN says, the clock is ticking for the quarter of a million civilians still trapped in the city.>> Because this part of eastern Aleppo is effectively being besieged, the humanitarian situation inside is getting increasingly worse.
And international agencies have repeatedly called for free access to humanitarian care and also for a halt in bombing on the area.>> Aleppo's been divided between government forces and rebels since the conflict erupted in 2012. Seizing full control would be the biggest victory for Syrian president Bashar al-Assad in five years of fighting.
And would demonstrate a dramatic power shift in his favor since allying with Russia last year.