While about 6,000 officers participated in a peaceful rally on Murray Street, more than 4,000 swarmed over police barricades, blocked the entry to City Hall and later marched onto the Brooklyn Bridge, where they tied up traffic for nearly an hour. Neither the leadership of the P.B.A. nor senior officers of the department were able to control them.

In a telling moment, Chief David W. Scott, the highest ranking uniformed officer in the department, was booed down by the crowd when he implored the officers to move off the steps of City Hall. "I'm disappointed in the fact that police officers would violate the law," Chief Scott said later.

Mr. Caruso and his aides also failed to persuade the splinter group to join the main rally. "Fellas, come on this way," Mr. Caruso said through a bull horn, his words lost in the cacophony.

The protest began shortly after 10 A.M. as officers who had been bused in from all over the city by the union started to march around City Hall Park. From the onset, the demonstrators' rhetoric was vicious. Bristling with banners and signs, the column stretched around the entire park and spilled past the blue sawhorse barricades onto Broadway and Park Row. The officers alternated chants of "No justice! No police!" with slogans like "The Mayor's on Crack."

Many officers wore T-shirts saying "Dinkins Must Go!" Hundreds carried hand-painted signs with sayings like "Dear Mayor, have you hugged a drug dealer today," "Dinkins, We Know Your True Color -- Yellow Bellied."

At 10:50 A.M., a few demonstrators chanting "Take the hall! Take the hall!" flooded over the barriers and into the parking lot in front of City Hall, meeting no resistance from the police on guard. Cheering and screaming, thousands of others poured through from every side of the park and seethed up the hall steps. Some mounted automobiles and began a raucous demonstration, denting the cars.

While the rowdier demonstrators refused to leave the City Hall area, most of the group crowded onto Murray Street between Church Street and Broadway, where they listened to sharply worded speeches from Mr. Caruso, Mr. Giuliani and, finally, Michael O'Keefe, the officer who was cleared by a grand jury recently in the shooting death of a Dominican man in Washington Heights. Many officers flooded the bars along Murray Street and drank openly on the street during the speeches. Bridge Blocked