WASHINGTON — A 2-year-old girl drowned and a 2-year-old boy is in critical condition following an incident at a pool in Sterling, Virginia.

Loudoun County officials responded at 10:43 a.m. Saturday for a possible drowning at a residence on Acorn Court in Sterling.

A family member discovered the two children unconscious in a pool.

They children were taken to the Lansdowne Campus of Inova Loudoun Hospital, where the girl died, and the boy is listed in critical condition.

A family member told NBC Washington that the two children are twins.