American troops and tanks Tuesday occupied a main plaza facing army headquarters, where four Haitians died in a firefight after discharged Haitian soldiers stormed the building to demand back pay.

During the night, American soldiers stretched concertina wire across much of the huge Champ-de-Mars plaza to block access to army headquarters.Tuesday morning, as U.S. soldiers watched from a distance of 30 yards, scores of youths began tearing apart an old, two-story gingerbread-style wooden home located behind army headquarters. The youths said Haitian soldiers used it to hide guns. Local businessmen said soldiers had lived there and in an adjacent concrete home.

When the youths began breaking into that home, too, two U.S. soldiers chased everyone away from both homes by spraying Mace at them. Hundreds gathered to watch.

Heavy tanks - rarely removed from the airport where they're kept - were positioned around army headquarters. During the night, floodlights from U.S. Army trucks lit up the plaza. Much of the plaza, a main traffic crossroads, was blocked off by concertina wire.

Scores of discharged Haitians soldier forced their way into the headquarters Monday and clashed with Haitian officers inside. At least four people were wounded in the fighting.

Immediately after the shooting broke out, several men in civilian clothes ran across the plaza carrying assault rifles. Witnesses said they were former soldiers who had broken into the armory and stolen weapons. Civilians later picked up rifles, grenades and other weapons dropped by the fleeing men and gave them to American troops. U.S. soldiers made at least a dozen arrests.