A 14-year-old boy who was rushed to hospital Thursday after being found at the bottom of a pool remains in critical condition.

The teenager was taking swimming lessons at the Pere Marquette Centre with his class when he was discovered to have not surfaced for several minutes.

The boy was pulled out of the pool by lifeguards who called 9-1-1.

Valerie Tremblay, chief of operations at Urgences Santé said three teams of paramedics rushed to the recreational centre next to a school.

"One of those had advanced life support so advanced care was given to the young man and he was transported in critical condition the hospital," said Tremblay.

The boy had a pulse but was not breathing on his own when he was placed in the ambulance.

One of the lifeguards was treated for shock.

Francois Lepine of the Lifesaving Society called the event rare.

“It's less than 1 per cent of all the drownings that occur in public pools, so it's a rare incident,” he said.

Lepine said there are regulations regarding safety in public pools that help prevent drowning, including ensuring teachers are trained in lifeguarding, or otherwise have a lifeguard monitor the course.

Drownings can happen very quickly, he said.

“It's less than a minute, so if you're in distress in the water and I don't know the circumstances, but if you're a non-swimmer and you're at the surface of the water, it could take less than 60 seconds to be on the bottom of the pool,” he said.

The Pere-Marquette Centre remained closed for the day.

Police were also on site much of the day, but described the event as an accident, not a criminal event.