At least 50 school students in Madhya Pradesh’s Chhindwara district were hospitalised on Wednesday after they allegedly inhaled ammonia gas that had leaked from a nearby cold storage nearby, PTI reported.

The incident took place at a Bhartiya Vidya Mandir school on Narsinghpur road in the district. Around 800 students were present on the campus when a few of them complained of uneasiness, an unidentified official told the news agency.

District Collector JK Jain and Superintendent of Police Gaurav Tiwari visited the campus, and have ordered an inquiry into the incident. “The students have been sent home from the district hospital,” Jain said. “We have evacuated the school…the owner of the cold storage is being questioned.”

Jain said the situation was now under control, and that the students were healthy and safe, reported The Times of India. “The gas only caused some irritation but major reason for the problem was panic,” Jain added.