PORT-AU-PRINCE (Reuters) — Shots and tear gas were fired Sunday near the presidential palace in Haiti’s capital, Port-au-Prince, during a protest organized by police officers demanding better pay and working conditions.

Officers told The Associated Press that at least three police officers were wounded.

It was not immediately clear who fired the shots or the tear gas during the protest, which coincided with the start of Carnival celebrations. A stage built by the Ministry of Defense and guarded by the army was also set on fire, a witness told Reuters.