A suspected gas leak caused panic at a school in Chennai’s Thiruvottiyur area, PTI reported on Friday. Students were evacuated and 30 girls were hospitalized, three of them in critical condition.

“Some of us had to rush out of the classroom for fresh air,” said one student. “Even our teachers had difficulty breathing, and some students fainted before the teachers revived them.”

According to PTI, some students felt nauseous and even vomited in class, though none had serious symptoms.

A student’s mother told ANI, “My daughter had difficulty breathing and vomited two days ago, and it happened again yesterday. Today she felt dizzy and vomited, but teachers told her not to act sick. The school did not inform us; we discovered out after she was admitted to a government hospital.We later shifted her to a private hospital, and she is still under observation.

After the incident, fire department officials were called in to help with rescue efforts.

An initial investigation suggests that a chemical leak from the school’s laboratory may have caused the students’ discomfort. Some reports also suggest that fumes from a nearby chemical plant could have contributed to the respiratory problems. Authorities are currently investigating the source of the gas leak.

NDRF Commander AK Chauhan said, “I cannot confirm the exact cause yet. Our team assessed the situation, and everything seems normal; we have not detected any gas.”