PORT-AU-PRINCE, Haiti – Police opened fire on a crowd of apparently peaceful protesters demanding the release of detainees loyal to the ousted president, Jean-Bertrand Aristide, and at least five people were killed, U.N. officials and witnesses said.

Wednesday’s shooting came as the U.S. State Department confirmed it plans to waive an arms embargo to allow sales of thousands of arms for the Haitian police, whom critics accuse of brutality, summary executions, and persecution of pro-Aristide loyalists.

U.S. officials and the interim Haitian government they helped install say the police are outgunned and outnumbered by politically allied gangsters.

Witnesses said police drove up behind demonstrators Wednesday and shot into the crowd as it approached the headquarters of the U.N. peacekeeping mission in Haiti’s capital, Port-au-Prince.

“The police started to fire,” said one witness, who spoke on condition of anonymity for fear of his safety. “People started to run and shout hostile slogans at the police.”

Five people were killed and an unknown number wounded, witnesses said.

The witnesses said the officers arrived in department pickup trucks and wore police uniforms and masks – standard uniform for the riot squad.

A U.N. mission spokesman, Damian Onses-Cardona, confirmed that police opened fire on demonstrators but had no further information.

A U.N. civilian police spokesman, Dan Moskaluk, said peacekeepers called to the scene after the shooting found five bodies. He called the march an “unauthorized, illegal demonstration.”