A floor-cleaning machine fuelled by propane may have been the cause of carbon monoxide poisoning that forced 73 children and about a dozen adults to leave a daycare in Saint-Eustache, Que., with some being rushed to hospital.

"At the moment we suspect a [piece of] equipment used to clean the floor that uses propane gas. That’s what we suspect," said Saint-Eustache fire Chief Charles de Rouville.

De Rouville​ said the floors at Garderies Les Petits Explorateurs — located at 217 Industriel Blvd. — were cleaned Monday night with the machine, which may have malfunctioned.

"We’ll know for sure tomorrow morning because we will take a sample of the air in the daycare all night long," he said.​

Guy Rollin picked up his son Zackary from the Saint-Eustache Hospital Tuesday afternoon after the two-year-old was treated for carbon monoxide inhalation. (Thomas Daigle/CBC) The daycare was not equipped with carbon monoxide detectors, fire officials confirmed.

Headaches and vomiting

Annie Daoust, communications co-ordinator for Saint-Eustache, said the incident happened at about 10:30 a.m. on Tuesday.

Quebec Families Minister Francine Charbonneau said public security officials were called to the daycare to test the air quality after several children and staff members fell ill.

She said their symptoms included headaches and vomiting. She said five children showed more serious symptoms than the others and two children fell unconscious.

"A heightened level of carbon monoxide was discovered," Charbonneau said.

After leaving the daycare building, the children and staff were taken by bus to the CSSS Lac des Deux Montagnes as a preventative measure.

Two children were transported to Sainte-Justine Hospital in Montreal as a precaution.

Charbonneau said a quick investigation was carried out on the site, and there is no longer any danger.

Prime Minister Stephen Harper heard about the incident and commented via twitter.

Psycho-social aid is being provided to families and daycare providers.

All parents with children at the daycare have been notified.

The daycare will remain closed until at least tomorrow morning.