(CBS News) LONDON -- Hundreds, by some estimates more than a thousand, are dead Wednesday in Syria, and Syrian rebels say they are victims of a poison gas attack that the Syrian government launched on the suburbs of Damascus.
The government strongly denies it.
The videos show nightmarish scenes, however. Rows of lifeless bodies, many of them small children.
Others appear to be dying. They're shown writhing in agony and in the grip of seizures.
The Syrian opposition claims this is the aftermath of a chemical attack on a residential neighborhood on the outskirts of Damascus.
It's not the first time we've heard reports of chemical weapons being used in Syria. But if this one is real, it's on a much larger scale.
The videos are impossible for us to verify. But chemical weapons expert and CBS consultant Hamish de Bretton-Gordon told us the symptoms look like those caused by nerve gas.
"The quivering bodies, pin-point pupils, the lack of any injuries or blood on the bodies and the mass casualties. These people have died from some unconventional weapon, and at the moment, the most likely explanation would be some sort of chemical weapon," said de Bretton-Gordon.
United Nations weapons inspectors who arrived in Syria this week could confirm whether chemicals were used, but the Syrian government hasn't given them permission to visit the scene.
On Wednesday, the Syrian regime denied allegations that it was behind the attack -- and it's refuted any charges that it used chemical weapons throughout Syria's civil war.
It's a conflict that's already cost more than a 100,000 people their lives.
In the last six days alone, more than 30,000 Syrian refugees have streamed across the border to Iraq -- driven from their homes by a war that only seems to get more vicious by the day.