A bomb threat forced the temporary evacuation of Dacula Middle School early Wednesday afternoon. But school leaders later determined the letter was a prank.

A school employee found the written note and the building was evacuated, according to Sloan Roach, spokeswoman for Gwinnett County schools. Investigators determined the threat was a prank and students were allowed to return to class, Roach said.

The threat did not affect dismissal time at the school. A letter to parents about the incident was sent home with students, Roach said.

"While the search did not find anything of concern, the safety of our students is our main priority and the evacuation of our school was a necessary precaution," Principal Kellye Riggins wrote in the letter.

The Dacula school's incident was the second in metro Atlanta believed to be related to a prank.

Earlier Wednesday, about 100 students at Douglas County High School were pepper-sprayed in an apparent prank, according to police. One area of the school was evacuated.