Hundreds students at a school in Tianshui, central China, had to be hospitalised for smoke inhalation following a fire drill.

The school was said to have used smoke machines to increase the realism of the drill on September 18, which unfortunately back fired, reported People's Daily Online.

A total of 193 students were admitted to hospital for symptoms including vomiting, while 139 remains hospitalised for observation and treatment.

Tianshui Yifu Experimental High School staged a drill with heavy smoke in Tianshui, China, on September 18

Close to 200 students were admitted to hospital for smoke inhalation after the drill. 139 remains in observation

According to reports, the heavy smoke mostly affected year seven pupils at Tianshui Yifu Experimental High School.

The average age of those affected was about 12.

An unnamed year eight student, who was in another building, recalled: 'When the alarm sounded, our year went out of the building very quickly.

'The school had prepared to disperse smoke in the year seven building so they had to wait before they came down.'

However, situation quickly escalated when these students did not following instructions.

The year eight student explained: 'When the smoke started, some of the students didn't immediately go downstairs.

'They were playing in the middle of the heavy smoke.'

According to the witness, students continued to play despite teachers telling them to 'cover their mouth and nose with a wet handkerchief and make their way downstairs'.

Photographs from the scene show that smoke was emanating from several different parts of the school.

In fact, students say the smoke had drifted to other parts of the school and students had experienced choking sensations there.

After the drill, most of the students returned to class.

Remaining on the the school's courtyard were the year seven students who suffered from heavy smoke inhalation and were seen lying on the ground.

In the past, real fire has also be used as part of fire drills at schools. Above, students duck flames in Shanghai

Many students suffered from symptoms including vomiting, fever, dizziness and even facial swelling.

A total of 193 students were reported to have been taken to three local hospitals.

Of those, 5 people were in critical condition and 4 were severely affected by the smoke.

At the moment, 139 students remains in hospital for observation.

There were no deaths reported and the students appear to be stable.

Institutions, including work place and schools, in China are legally obligated to conduct regular fire drills.

In the past, real fire has also be used as part of fire drills at schools.

Local authorities in Tianshui have expressed that stricter rules will be enforced in future drill to prevent similar incidents in the future.

It is not clear whether the school will face any disciplinary action following the incident.