Emergency responders were called to Stephen F. Austin High School of Dumble Street around 11am.
We spoke to a man who was delivering a cabinet to the school. He said he was moving the cabinet inside when he first noticed the leak. Ten minutes later, there was some kind of cloud, he told us.
Hazmat cleared the building. According to officials, they found three different kinds of acid leaking from containers that were being moved into the school for chemistry labs.
No one was injured, the building was not damaged and there was no danger to the public, authorities said.
Fire crews ventilated the school and said it will re-open at its regular time.