Police in Newmarket are crediting a young girl with calling 911 after her babysitter was found unresponsive in a backyard pool Friday afternoon.

York Regional Police said members of Central York Fire Services were the first to arrive at a home on Arnold Crescent around 4:45 p.m. 

Sgt. John Loughry said a firefighter dove into the pool and pulled the woman out. That firefighter then performed CPR until paramedics arrived.

Loughry could not confirm the woman's condition but said "life saving measures are continuing" at hospital.

Next of kin has been notified.

Insp. Alvaro Almeida with York Regional Police told CBC Toronto the child who called 911 tried to rescue the babysitter. Her age is not being released.

Loughry said police are treating this as an accident. He said it doesn't appear there was a party going on at the time, and alcohol is not believed to be a factor.

It's still unclear how the woman entered the pool. Foul play is also not suspected.

york pool drowning

Paramedics performed CPR on the woman before she was taken to hospital, York Regional Police told CBC Toronto. (CBC)

With files from Natalie Nanowski