Authorities are investigating who phoned in a false bomb threat to Mission High School.

Mission CISD officials confirmed the incident in a message sent out on Twitter on Thursday afternoon.

School officials said the threat was telephoned to the Mission Police Department around 2:45 p.m. Thursday.

Authorities evacuated the school for about 20 minutes while authorities searched the building.

School district officials reported that it was a false alarm and that students were allowed to return inside the building.