A 10-year-old boy was pronounced dead after he was pulled from a swimming pool outside a Newmarket residence early Saturday morning.

The boy had attended a pool party at the house on Woodfern Way near Yonge Street and Green Lane at around 5:30 p.m.

When the boy did not return home by 11 p.m., his family contacted police and a search was undertaken.

The host of the party then found the boy in the pool at around 2:45 a.m., according to York Regional Police.

The boy was pronounced dead at the scene.

A cause of death has not yet been determined.

"Our investigators are conducting interviews as we speak. They have been conducting interviews throughout the night and there are more to follow," Const. Blair McQuillan told CP24 Saturday.

"What they are trying to do is establish the timeline between when the child left the home and the time that he was found this morning, so we can establish what exactly transpired."

Anyone with information about the incident is asked to contact York Regional Police at 1 (866) - 876 - 5423, ext. 7141.