A chemical mix-up at Maricopa High School prompted a heavy emergency response this morning, the third day of school. 

Firefighters were dispatched to a reported structure fire at the high school around 8 a.m., but quickly learned there was no fire, according to the city’s public safety spokesperson, Monica Williams. 

“An alarm was triggered in a science classroom,” Williams said. “We have now determined that to be from two chemicals mixing in a sealed mixing container.” 

The incident appeared to be caused by a “malfunctioning hood/exhaust system,” Maricopa Unified School District Director of Communications Mishell Terry said in an email to InMaricopa. 

The fire department “quickly responded and has cleared the building for reentry,” Terry said. “All students and staff are safe, and normal school activities have resumed.” 

Students in the 100 building were evacuated for 30 minutes and then allowed to return inside. 

 “We appreciate the swift action of the fire department and the cooperation of our students and staff,” Terry added. 

Maricopa Fire and Medical Department called for a hazmat team to assist.