A fifth-floor glass window of Nava Nalanda school crashed on two students just when they were gathering for the morning assembly on the first day of the new session on Monday.

One of the students was critically injured and has been admitted to hospital with multiple injuries. The other suffered fewer injuries and was discharged from hospital after first aid, police said. Both are Class IX students.

The accident was reported around 7.05am, minutes before the morning assembly was to start at the Southern Avenue institution.

Guardians complained of negligence by the school. Some alleged there was no ambulance to take the bleeding child to the hospital. Some accused the school of overcharging.

Police said no complaint was lodged till late on Monday evening.

Priyam Das, 14 and Srinjay Roy, 13, were rushed to different hospitals.

Srinjay, who was treated and discharged from NG Nursing Home, said it felt like a “cupboard” fell on him.

“I had just entered the school compound and we were getting ready for the assembly when suddenly something heavy hit my head. It felt like a cupboard. The next moment I saw my friend Priyam lying on the ground with glass all over. He was bleeding,” Srinjay told Metro after being discharged from the hospital.

Srinjay’s mother Barnali complained that she learned about the accident from a guardian and not from any school official.

Priyam, whose mother is an employee of RG Kar Medical College and Hospital, shifted her son to the government facility from a private hospital where he was taken initially.

“Priyam got hurt on the head and left shoulder. He was bleeding but conscious throughout. I took him to an adjacent nursing home but they referred him to another private hospital,” said Rumeli Sarkar, a history teacher at Nava Nalanda.

“The boy was taken to a government hospital in north Calcutta at the insistence of his mother,” Sarkar said.

The teacher said she was standing at the gate when the accident happened.

“It was almost 7.05am. The gate was supposed to close and the prayer was to start. Suddenly, I heard the sound of glass pieces falling to the ground. I left the gate and saw the students in panic,” said Sarkar.

Srinjay was given preliminary first aid in the school before he was taken to the adjacent nursing home.

“It was an unfortunate incident which should not have happened. A shade could have prevented an accident like this but we cannot put a shade because of fire safety rules,” said principal Arijit Mitra.

“A student on the fifth floor tried to open the sliding window and somehow the glass broke and fell,” he said.

Mitra said they have decided to put up a net cover since a shade cannot be installed.

“The driver of the school ambulance, who was not present when the accident happened, has been showcaused,” Mitra said.

The Southern Avenue campus of Nava Nalanda is for students from Classes VII to X and runs in two shifts — morning and day. Nava Nalanda runs from several campuses in south Calcutta.

Guardians agitated infront of the Southern Avenue building and demanded an explanation from the authorities for the accident. Till the second shift on Monday, which ended at 4.40pm, cops were deployed on and outside the campus.

“The fact that glass pieces fell on a student shows there were some maintenance lapses on the part of the school,” said the mother of a Class VII student.

“A family friend who accompanied Priyam’s mother to the hospital told us in the evening that he had been administered stitches and shifted to the ward,” said history teacher Sarkar.

Priyam’s family did not answer calls or respond totext messages from this newspaper.