Students at St. Matthew Catholic School were evacuated Tuesday morning after a "cleaning liquid" spilled in the science lab there.
San Antonio Fire Department spokesman Christian Bove said a hazmat team responded to the school, which is located near the intersection of Wurzbach and Vance Jackson, to contain the spill.
Bove said the spill is small -- less than two cups -- but that students were evacuated to the school's McDonald Family Center, a gymnasium and recreation center, as a precaution.
Three faculty members and one student were evaluated by emergency crews. The student wound up going home for existing respiratory problem; the three faculty members are OK.
Bove said the liquid that spilled was nitric acid, however the school's principal said he believes it was a cleaning compound.
Parents were alerted to the spill via text message.
Once the affected area is cleaned and cleared by the hazmat crews, the principal said students will be sent back to class.