The blaze erupted in a music room on the fourth floor of Takinogawa Dai-san Elementary School in Tokyo’s Kita district, sending thick black smoke billowing from the building and triggering an emergency response involving 75 fire engines and dozens of firefighters.

All pupils and staff were evacuated safely, and firefighters brought the blaze under control after approximately three hours, media reports said.

Most of the injured suffered from smoke inhalation, according to Kyodo News. Four people were reportedly rescued from inside the school building during the operation.

Witnesses described scenes of confusion as helicopters circled overhead and parents rushed to the school to collect their children.

One eyewitness said several children escaped through classroom windows onto a concrete ledge before firefighters used ladders to bring them to safety.

A sixth-grade student said she and her classmates first noticed the smell of smoke while attending lessons two rooms away from the music room where the fire reportedly began.

“We thought maybe someone was cooking. Then the siren went off,” she said.

The student said children covered their mouths with handkerchiefs as they descended the stairs and evacuated to the school grounds.

“Then we saw the music room already burning with flames,” she said, adding that she heard a loud bang from an area between the music room and an adjacent multi-purpose room.

“It was scary, and a lot of kids were crying,” she said.

Authorities have not yet announced the cause of the fire, and investigations into the incident are ongoing.

Takinogawa Dai-san Elementary School is located in the northern part of Tokyo and serves students from the surrounding residential area.