PORT-AU-PRINCE -- (AP) -- An armed gang opened fire on thousands of antigovernment protesters Monday during a clash that killed one man.

The gunmen were in a truck when they shot at the crowd. Riot police returned fire.

It was not immediately clear who shot the man or whether he was an antigovernment demonstrator, Aristide partisan or bystander.

The attack came a day after U.S. Ambassador James Foley signed a communiqué exhorting the police to protect the demonstrators against ``armed gangs.''

Since mid-September, at least 23 people have been killed during antigovernment demonstrations around the country.

Monday's demonstration was one of the largest yet in the capital, beginning with 200 and swelling to 10,000 people.

Some in the crowd waved white handkerchiefs to symbolize peace, while others held red cards used in soccer to eject players in a call for Aristide to step down.

Aristide, who became the Caribbean country's first freely elected president in a landslide, has been struggling to maintain support. In recent weeks, Environment Minister Webster Pierre, Education Minister Marie-Carmel Paule Austin and Tourism Minister Martine Deverson resigned amid increasing violence. The vice president of an interim electoral council also resigned.

Many have alleged that the government has tried to repress antigovernment demonstrations by using the police to break them up or by allowing Aristide supporters to use strong-arm tactics against opponents.

Aristide was ousted in a 1991 coup and restored to power in a 1994 U.S. occupation. He stepped down in 1996 because of a term limit and was reelected in 2000. Aristide has refused opposition calls to step down, saying he will serve out his term until 2006.

In the meantime, the terms of most members of the Senate and the Chamber of Deputies are set to expire Jan. 12. Aristide will be forced to rule by decree if no solution is reached by then.