CREATED Jul. 15, 2013 - UPDATED: Jul. 16, 2013
Instead of mourning the life of one child, a family in Oakland County is mourning the loss of two of their children.
After 11-year-old Alex Mansour died Sunday from injuries due to the boating accident on Sylvan Lake, his six-year-old sister Gabrielle died on Monday.
10-year-old Adriana Mansour is in critical condition at Beaumont Royal Oak.
On Sunday afternoon, the three siblings were tubing behind a jet ski when a boat crashed into the tube.
The boater is reportedly cooperating with investigators, who say they don't believe alcohol was involved in the incident.
One child is dead and two others injured after a tubing accident on Sylvan Lake in Oakland County Sunday.
A power boat collided with the tube the children were being pulled on, killing a boy and seriously hurting his two sisters.
The Keego Harbor Sheriff's Department is investigating the accident.