HOUSTON -

The Houston ISD added security at Carnegie Vanguard High School after an anonymous threat was made online Monday morning.

The Houston Independent School District didn't release the type of threat made against the school, located at 1501 Taft Street in Houston's Montrose neighborhood.

"Oh my God. I was so nervous because she was texting me and texting me," said Blanca Munoz.

Munoz went to the high school to pick up her daughter Marisol.

"She sent me a text and told me she was so scared. She was crying and I just came to pick her up," said Munoz.

The school's principal issued a phone message, saying in part: "This morning I was made aware of an anonymous online posting threatening the school. I want to ensure you that school and district personnel take these threats seriously and will do our utmost best to ensure safety."

"They say they have everything in control but I didn't feel that way so that's why I came for my daughter," said Munoz. "Too many bad people doing this kind of stuff in the school and I just didn't feel good at home for somebody to tell me they started shooting at the school and something happens to my daughter."

HISD police are investigating.