Kenyan police fired tear gas at a crowd of children protesting the seizure of their school playground by a property developer on Monday.

About 100 children between eight and 13 years old from Langata Road primary school in Nairobi, along with a smaller group of parents and activists, converged in front of a newly built wall that separated their school building from a playing field, which had been built over a holiday.

As the children tried to access the playground, roughly 40 police officers who responded to the scene fired tear gas canisters at the crowd, forcing them to disperse. Officers also reportedly brought police dogs to help them break up the crowds.

Agence France-Presse reported that the dozens of children who were caught choking in the fumes ran to take shelter on a pedestrian bridge nearby.

In a video published by Reuters, the crowd can be seen pushing against the barriers that separate the field from the school building, forcing open the gate and breaking down a smaller cement section of the wall amid cheers of celebration. Some of the children held up signs proclaiming, “Kenya: Land of the shameless grabbers” and “Land Grabbing is Terror Against Children.”

Activist Boniface Mwangi told Al Jazeera, “The children were peaceful and all they wanted was access to their playground during break time. The children walked peaceful to the gate that has been set up by the grabber and police responded with tear gas. A few of them were injured.”