Lifeguards are being credited with saving a teenager's life after he nearly drowned in a pool at his Georgetown high school.

Halton Regional Police say the 16-year-old was overcome by a medical condition while swimming inside Georgetown District High School just before 8 a.m. on Thursday.

The boy was unable to swim to the side of the pool and went under water. Lifeguards noticed the submerged teen, and pulled him out.

The victim had no vital signs and lifeguards immediately began CPR. They revived the boy by the time paramedics arrived, police said.

The teen, who is a student at the school, was taken to a local hospital. Doctors say he is doing fine and is expected to make a full recovery.

Police believe a pre-existing health condition led to the boy's distress.

The lifeguards are expected to receive a police citation for their actions.

With a report from CTV Toronto's Jim Junkin