Students at Highland Park Middle School and Arch H. McCulloch Intermediate School have been evacuated due to smoke in the building.
The schools are in the same building at 3555 Granada Drive in Dallas.
NBC 5 has learned all of the students and faculty were able to get out of the building without injury.
Firefighters searched for the source of the smoke but no sign of fire was found. It was later determined that the city was conducting a smoke test in the sewage system, and smoke from that test entered the school.
The area was determined to be safe and the students were allowed to return to class.
