It happened over Memorial Day weekend, according to police. Officers responded to an alarm at the school's campus on Steward Creek Road on May 24.
Police said the two girls vandalized a portable building and caused significant water damage to other parts of the campus.
The girls appear to be between 12 and 16 years old, according to investigators. They're wanted for first degree criminal mischief.
Anyone with information is asked to contact Crime Stoppers at 1-800-392-STOP (7867) or the Montgomery ISD Police Department at 936-276-2200
You can also leave an online tip by clicking here.