Fifty-four children and nearly 20 adults were sent to a Winnipeg hospital Thursday after levels of carbon monoxide were detected inside a daycare.

The Peek-A-Boo Infant Child Care was evacuated after CO detectors went off. The children, who range in age from a few months old to about six years, all appear to be in good condition, according to health officials.

The children and staff were removed from the building and assessed by medical staff on three buses as they were taken to hospital.

Jan Ranson, the daycare's director, said the carbon detectors were recently installed.

"Our furnace company suggested we get them, just to be extra safe," she said. "So we got them. We've had them for about a week."

Manitoba Hydro spent the day trying to find the source of the leak. It was eventually traced to at least one rooftop gas heater.

Corrie Balas, whose daughter attends the daycare, worried what would have happened without detectors.

"If they didn't have an alarm, who knows how long they would have been in there for?" she told CTV News.

Bill Clark, assistant chief of operations with the Winnipeg Fire Paramedic Service, said even low levels of carbon monoxide are potentially dangerous.

"With the low level, it's over a period of time, and there are usually other symptoms that kick, in such as nausea or headache or vomiting, he said.