That's the report from the BBC:
A team of UN inspectors arrived in Syria on Sunday to probe earlier allegations of chemical weapons use.
Syria's state-run news agency said that the reports were "baseless" and an attempt to distract the inspectors.
UK Foreign Secretary William Hague expressed "deep concern" and called for the Syrian government "to allow immediate access to the area" for the investigators.
If confirmed, the attacks would mark a "shocking escalation in the use of chemical weapons in Syria", Mr Hague said.
The Arab League echoed the call for the inspectors to go to the site, AFP reports.
The attack took place as part of heavy government bombardment of the region surrounding Damascus, where government forces have been trying to drive out rebel forces.
Casualties were reported in the areas of Irbin, Duma and Muadhamiya among others, activists said.
Footage uploaded to YouTube from the scene by activists shows many people being treated in makeshift hospitals.
The videos show victims, including many children, having convulsions. Others are apparently immobile and have difficulty breathing.
The impact to Obama's weekend golf plans have yet to be assessed.
UPDATE: It was a year ago today, interestingly enough, that Obama gave his 'red line' statement:
We cannot have a situation where chemical or biological weapons are falling into the hands of the wrong people," Obama told reporters at the White House. "We have been very clear to the Assad regime -- but also to other players on the ground -- that a red line for us is we start seeing a whole bunch of chemical weapons moving around or being utilized.
"That would change my calculus; that would change my equation."
How's that calculus coming Mr. President?