Evidence of another deadly attack in Syria has surfaced, this one with an incendiary agent, opposition activists said Friday.
Seven people died and dozens were wounded Monday in the attack on a school in northern Syria, they said.
The allegation comes as U.S. President Barack Obama considers military action against the regime of Syrian President Bashar al-Assad after what U.S. officials and chemical weapons experts say was a chemical weapons attack on the outskirts of Damascus on August 21.
Videos that activists said had been shot in the Urum Al-Kubra village of Aleppo province after the Monday attack show people with severe burns, but no other external injuries.
Some people reported hearing nothing before chemicals started to burn them.
"It's like they used chemicals, like napalm or something," said a doctor at a local hospital who confirmed the casualties. "It's causing a lot of burns."
CNN has not been able to independently confirm the accounts.
An expert who saw the videos, which were broadcast Thursday on the BBC program "Panorama," said they did not appear to show the aftermath of a chemical weapons attack.
"You could see burns around the school, the playground, it looked like there had been a fire," said Alastair Hay, professor of environmental toxicology at the University of Leeds, in a telephone interview. "Chemical weapons don't cause that sort of destruction.
Hay, who advises the British government on chemical weapons issues, applauded Parliament's decision not to back British involvement in military action against the government in Damascus.
"I think the U.N. process should be allowed to run to completion," he said, referring to Secretary-General Ban Ki-moon's request that the Organization for the Prohibition of Chemical Weapons carry out an investigation on his behalf.
The OPCW oversees the Chemical Weapons Convention, which bans the production, stockpiling, and use of chemical weapons and has been signed by 189 countries. Syria has not.
If the OPCW were to find that chemical weapons had indeed been used, that would pressure China and Russia -- which have signed it -- to support some action against Syria, Hay said.
"These governments have been supportive of the OPCW; it would be very difficult for them to ignore a report produced by the OPCW's inspectors."
It is the indiscriminate nature of chemical weapons that puts them in a particularly abhorrent category, noted Hay, who said he was confident they had been used in Syria.
"All of the features that I saw in all the videos that I've seen, with individuals having no evidence of trauma, having great difficult breathing, suggests exposure to something that is causing asphyxia," he said. "Chemical agents in the nerve-agent category do this."
Still, he added, "I'd like to see the final proof."
If the OPCW were to conclude that chemical weapons had been used, the debate would then turn to who used them.
The manufacture of chemical weapons such as sarin is a technique known to very few, he said. "It's a very dangerous process because the chemical is so toxic, and you have to make sure that there's protection for those involved in making it. Otherwise, they will die."
Putting the chemicals into a weapon requires another set of skills that are known to very few people, he said. "It's not something you can do in your lockup or your garage; it would, obviously, point to somebody like a government having these weapons."
Obama's talk about the use of chemical weapons crossing a "red line" appears to have put him into a corner, Hay said. "It's difficult to know how he's going to back out of that one, without some kind of punitive strike."
Hay said he hoped any military action would not be against al-Assad's chemical weapons stockpiles because "that runs the risk of spreading these agents even further."
The alleged use of chemical weapons in the August 21 attack in a suburb of Damascus was only the latest of more than a dozen such reports in recent months, according to Jon Day, the chairman of Britain's Joint Intelligence Committee.
"We have assessed previously that the Syrian regime used lethal CW (chemical weapons) on 14 occasions from 2012," he said Thursday in a two-page report to Prime Minister David Cameron.
If what Day described as "a clear pattern of regime use" of chemical weapons has indeed been established, why did the latest report spark a more bellicose response from world powers?