43 to hospital after suspected carbon monoxide leak Canadian officials say 43 people have been taken to hospital following a suspected carbon monoxide leak at a Montreal school.

MONTREAL -- A suspected carbon monoxide leak at a Montreal primary school led to the hospitalization of 35 children and eight adults Monday.

A spokesman for the ambulance service said students at Ecole des Decouvreurs in the Canadian city's LaSalle neighborhood reported nausea, dizziness and vomiting. Between 15 and 20 people, including one adult, were initially affected.

But after the school was evacuated and children were moved to a neighboring school, another wave of children and teachers complained of symptoms.

The illness could be related to carbon monoxide poisoning, but the cause has not been confirmed, Stephane Smith of Urgences-Sante said. In a letter to parents published online, the school administration raised the possibility of a problem "related to the heating system."

At around 12:30 p.m., Montreal Children's Hospital declared a code orange, which is used for an emergency situation with multiple victims. Dr. Robert Barnes, the hospital's associate director of professional services, said the 12 patients received there were in stable condition and under observation in the emergency room.

He could not confirm whether they would be discharged Monday.

Ste-Justine Hospital, Montreal's other pediatric facility, reported that it had received 22 students from the school, none of whom was in serious condition.

Firefighters inspected the school, but the school administration could not say Monday afternoon whether it would reopen Tuesday.