Firefighters were called to Browne Middle School on Sprague Drive in Dallas Thursday morning.
A spokesperson for Dallas Fire-Rescue tells NBC 5 that an employee noticed smoke coming from a window-mounted heating/air conditioning unit.
A spokesperson for the district says there were no students in that portable classroom.
Students say the alarm went off, and they all went outside, before they were cleared to go back in.
One parent went right to the school when she heard about the fire.
“Thank God everything is okay and they are back on their normal schedule,” said mother Devin Price.
Officials also said there was no damage to the building, just the window.
