10 people, including four children between one and 16 years old, were taken to hospital for CO exposure Saturday morning.

Paramedics and firefighters were called to a northeast Calgary home early Saturday after a number of people, including a one-year-old toddler, mysteriously fell ill.

EMS says at about 4 a.m., they got a call about someone in medical distress in a home in the 1800 block of 4 Street N.E.

When they arrived along with firefighters, they determined there were extremely high levels of carbon monoxide (CO) in the house.

"There were a total of nine occupants in the home when EMS arrived, including four children and a 10th occupant who had been in the home but had left the scene," said Calgary EMS spokesperson Stuart Brideaux.

All 10 occupants of the home were taken to hospital for exposure to CO.

"Six adults to Foothills and the Peter Lougheed hospital as well as four pediatric patients to the Alberta Children's Hospital."

Brideaux says the children ranged in age from one to 16 years old.

CO is an odourless, colourless and tasteless gas that blocks your body from getting the oxygen it needs to survive. The symptoms of exposure are very similar to other common ailments such as lethargy, headaches and nausea.

Brideaux says it was very fortunate they were able to get to the home to help out the patients because the level of CO could have become lethal in a very short time.

"In this case, all will require further assessment," he said. "It was a very dire situation, but it could have been worse."

He adds it is essential for all homes to be equipped with working smoke alarms and CO alarms on each level.

"They are very easily purchased at many locations, even battery operated ones. In newer homes they are often hardwired into the homes. Having a CO alarm outside of every bedroom on every level would be the best advice."

It's believed that a furnace inside the home was not venting properly, but fire officials and ATCO are at the scene to make a final determination.