The 20 were rushed to Ndola Central Hospital and treated for various injuries.
According to information obtained by The Post, council officers in the early hours of yesterday swung into action to demolish makeshift stalls at Chifubu market.
When the marketeers found that their stalls had been demolished and upon seeing that there was a heavy police presence in the area, they began rioting and damaged some shops within the market premises.
The marketeers threw stones at the police who in turn began firing teargas canisters but in the process, the tear gas landed into a nearby school Temweni High School.
This angered the pupils who joined the riot by throwing stones at the police.
About 10 pupils collapsed as a result of the tear gas and were immediately rushed to a nearby private clinic within Chifubu and later to Ndola Central Hospital.
Ndola Central Hospital public relations officer Sheona Chalimbana confirmed that a total of 20 people including teachers and pupils had been rushed to the hospital.
Chalimbana said the victims were treated for various injuries.
Efforts to get a comment from Copperbelt police commanding officer Antoneil Mutentwa failed as his phone went unanswered by press time.
Meanwhile, Ndola City Council public relations manager Roy Kuseka confirmed that the council carried out a demolition exercise to remove illegal structures that had been built on undesignated areas.
Kuseka explained that the marketeers whose stalls were demolished were encroaching on a road that passes between the market and the shops thereby causing an inconvenience to traffic.
He said the council would not allow illegality because in case of any accident, people would still blame it for not taking action.
Kuseka advised marketeers to trade in designated places.