A hospital in Syria's northern Idlib province was hit soon after the area was bombarded with a suspected chemical agent, an AFP correspondent reported.
The Britain-based Syrian Observatory for Human Rights monitoring group said there were 11 children among the dead. The Syrian medical relief group UOSSM reported that the overall death toll had been elevated to 100, according to Reuters.
Mohammed Rasoul, the head of a Syrian ambulance service, told the BBC that first responders found people choking in the streets.
"Our team is still there, moving patients from one place to another because of overcrowded hospitals," he said. "I am speaking to my team and they are doing fine, but the situation over there is very bad and most of those who are suffering are children."
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.