The Britain-based Syrian Observatory for Human Rights monitoring group put the death toll at 58, saying there were 11 children among the dead. Meanwhile, the Idlib Media Center said dozens of people had been killed.

The media center published footage of medical workers appearing to intubate an unresponsive man stripped down to his underwear and hooking up a little girl foaming at the mouth to a ventilator.

There was no comment from the government in Damascus or any international agency in the immediate aftermath of the attack.

It was the third claim of a chemical attack in just over a week in Syria. The previous two were reported in Hama province, in an area not far from Khan Sheikhoun, the site of Tuesday’s alleged attack.