BASTROP COUNTY, Texas (CBSDFW.COM/AP) – Three sisters — a high school junior, an eighth grader and a sixth grader — from Huntsville and a friend died in a two-vehicle crash in Central Texas as they traveled to watch a drill team competition in San Antonio, officials say.

The Texas Department of Public Safety says the wreck happened Friday night on westbound Texas 21 near Bastrop. A pickup truck rear-ended the girls’ stopped vehicle waiting to turn.

Authorities told CBS Austin that surveillance video shows the pickup truck not stopping “until .6 seconds prior to the crash, indicating possible distraction (cell phone) in the vehicle.”

The Huntsville Independent School District released a statement on Facebook that said three siblings died. Their mother, who was driving, was hospitalized in critical but stable condition. The fourth girl who died was a 2018 Huntsville High School graduate.

“The Huntsville ISD community is deeply saddened to learn of the deaths of three of our students and one former student as a result of a car accident that occurred in Bastrop County late Friday evening,” the district said. “…The death of any young person, much less four, is a loss that, in one way or another, affects us all.”

The identities of the victims have not yet been released.

DPS says the pickup driver and a passenger weren’t hurt.

Huntsville is 60 miles north of Houston.

(© Copyright 2019 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)