CHAMBERS COUNTY, Texas -

A Mother's Day family outing on the Trinity River ended in tragedy.

According to the Chambers County Sheriff's Office, a family from the Mont Belvieu-Dayton area in Chambers County were boating on the Trinity River to celebrate Mother's Day.

The father was driving the family boat, pulling his children on a large tube behind the boat.

According to investigators, the tube struck a partially submerged tree after rounding a bend in the river near the Chambers and Liberty County line, throwing the teens into the water.

Brooke Theiler, 16,was seriously hurt, and was taken via LifeFlight to Memorial Hermann Hospital, where she later died.

When the remaining family members arrived at the hospital, Theiler's older brother, 24, was admitted and rushed into surgery.

He is now listed in stable condition. No other injuries have been reported.

"This is tragic because this is a family that was doing everything responsibly. Safe boat. They had all of the safety equipment that you would need and want for the boat. We don't think there was extreme speed involved in it. This is just truly a tragic accident," said Chambers County Sheriff Brian Hawthorne.

This case is being investigated by the Texas Parks and Wildlife with assistance from the Chambers County Sheriff’s Office.

Deputies say they went out on the water Monday to look at exactly where the accident happened and the investigation is nearly wrapped up.