Ugandan police fired tear gas Monday to halt a protest in the capital against high food prices.

Witnesses say the police action dispersed protesters who had gathered in the Kiseka Market area of downtown Kampala.

The protest had been called by Activists for Change, an opposition group that was involved with so-called “walk to work” protests earlier this year.

Ugandan authorities used force to stop those protests and have vowed to shut down any renewal of the demonstrations this week.

On Sunday, police arrested at least 12 Activists for Change members on charges they were planning disruptive activities.