Parents at an Elmwood Park elementary school that was closed Friday say that their children were exposed to carbon monoxide despite school officials saying that wasn’t the case.

Several students and staff members at Gantner Avenue Elementary School fell ill Wednesday. More people became sick Thursday, prompting school officials to close the school Friday.

It was initially reported as a carbon monoxide incident, but officials then said that wasn’t the case and that the chemical glycol leaked from the HVAC system.

But parents tell News 12 New Jersey that their children did test positive for carbon monoxide exposure and at least one child had carbon monoxide poisoning, with a level of 13.

Parents are now demanding answers from school officials.

“This cannot happen again. You can’t do this to parents,” says mother Veronica McDowall.

McDowall says that her son did not feel well Wednesday afternoon when the school was evacuated. She found that he had carbon monoxide exposure after he had complained about headaches.

School officials say that none of their carbon monoxide detectors or tests picked up traces of the gas.

Some parents tell News 12 that they will not allow their children back into the school Monday until they feel confident that school officials know what is making everyone sick.

Elmwood Park Public Schools Superintendent Anthony Grieco says that he will have a comment on the situation over the weekend. He says that he hopes to have updated test results from the school.