HURST, Texas (CBSDFW.COM) – Officers in Hurst remain at L.D. Bell High School a day after students started receiving threats via text message. Police say students have continued to receive those threats during the last 24 hours.

Authorities on Wednesday were made aware of messages that threatened school safety. Officers conducted a sweep of the building and stayed at the school through the school day.

HEB ISD Superintendent Steven Chapman sent a letter to parents today saying, “We believe this may be an attempt by a student, or group of students, to disrupt the normal operation of L.D. Bell High School. At this time, we have shared all the information we are able to without compromising or impeding the ongoing investigation.”

Chapman also said that absences for Wednesday and Thursday will count as excused.

The contents of the messages were not released.

According to police, the threats didn’t trigger a lockdown and classes will go on as normal.

It is currently unknown about how many more students received the text threat in addition to the 15 that police reported on Wednesday.

Police said although they cannot release details on the investigation, they are monitoring social media and looking into the threats.

The school district sent a message to parents that read in part:

“Investigations are continuing at the local and federal levels. In an abundance of caution, additional police are on campus today… Making a threat against a school, even if intended as a joke, is an extremely serious offense. It is critical that students understand that actions like these will have serious repercussions.”