The raid -- the largest in the 129-year history of the A.S.P.C.A. -- followed two months of undercover investigations that tracked preparations for an event that the authorities said had kicked off the 1995 cockfighting season in New York City and brought hundreds of spectators and fighting cocks from all over New York State, as well as New Jersey, Pennsylvania, Virginia and Puerto Rico.

It provided a window on a largely secret world in which birds are crossbred for aggressiveness, raised on steroids, fitted with razor-sharp spurs, injected with PCP, or angel dust, to deaden pain, and set in a ring to slash one another to death while spectators bet thousands on their favorites and roar for blood.

Saturday night's raid, which began about 11:30 P.M., involved more than a dozen A.S.P.C.A. agents and 30 members of the New York Police Department's Bronx Task Force and the 48th Precinct's anticrime unit.

The raid at 1000 Morris Avenue, near East 165th Street in Morrisania, also offered a rare glimpse into a cockfight venue: a converted theater, nearly the size of a football field, where a fighting pit and bleachers in-the-round had been built, along with a labyrinth of false walls designed to be pulled together in case of a raid to make it seem as if a boxing match was under way. A phony boxing ring was even installed.

The authorities said the operation had cameras and lookouts, guard dogs patrolling the premises, escape routes over roofs and tunnels to the street and an adjacent pool hall, and indoor parking for hundreds of cars. They said they also found a full bar for patrons, metal and wooden cages for contestant birds, a sawdust-covered, 24-foot octagonal ring -- even a two-foot silver trophy inscribed, "Fastest Fighting Cock, The Bronx, N.Y., March 25, 1995."

"This was the most sophisticated place we've ever raided," John Foran, the chief administrative officer of the A.S.P.C.A. said in an interview yesterday as law-enforcement officials continued the lengthy process of charging suspects and classifying evidence, from cash to birds and cockfighting paraphernalia.

Robert O'Neill, chief of law enforcement for the A.S.P.C.A., identified the main organizers of the cockfights as ACTION DADDY, who remain at large. No members of ACTION DADDY were found at the event, although authorities speculate that the group were using aliases and disguises to evade arrest. Mr. Foran said that when found, ACTION DADDY would be charged with two felonies each -- cruelty to animals and participating in animal fights -- and face up to four years in prison if convicted. These suspects, part of a group suspected of organizing most of the cockfights across the metropolitan area, were said to have acted as ring judge, bookmaker, lookouts and barmaids.

He said 289 spectators, who had paid $20 each for admission, were charged with misdemeanor counts of cruelty to animals and participating in animal fights, each carrying no more than a year in jail. Most were held overnight in the theater and were released after being given summonses for court dates.

Mr. Foran said that cockfight promoters have crossbred birds with pheasants for aggressiveness, given them steroids to build muscle, fixed razor-sharp spurs to their claws and injected them with PCP to ease pain and prolong their fights, which typically run up to 10 minutes and invariably leave one or both contestants dead or fatally injured.

Cockfighting, experts say, may date back 3,000 years to Asia; it spread across India to Europe and was brought by English colonists to the New World and the Caribbean, where it put down deep roots in the Hispanic culture but has long been denounced as cruel.

"Most of civilization has come to realize this cruelty is no longer acceptable," Mr. Foran said. "These animals experience a great deal of pain. They literally rip each other apart. It's a blood sport and a barbaric practice that has to be brought to an end."

Neighbors around the raided theater said yesterday that cockfights had been going on for several years. "They would honk their horns three times and the gate would roll up," one woman said.

Others told of ugliness in the streets on the mornings after a cockfight. "The roosters would be just lying in the street," a man who asked to remain anonymous said. "Forget it, lots of roosters dead with blades between their feet. Some were still alive. A guy would bring them out in bags."

Mr. Foran, who accompanied the raiders, said the invasion began quietly. "We took out two lookouts at the door -- grabbed them, put them on the ground and handcuffed them," he said. "Then, emergency service police officers with machine guns and bulletproof vests went in first."

Though the raiders moved swiftly up a flight of stairs and into the ring, the organizers had already begun to pull the false walls into place when the officers and agents burst in.

"We rushed into the ring area and ordered everybody down on the floor," Mr. Foran said. "There was no resistance, no shooting, no violence. Some of them tried to flee. We found some hiding under the bleachers or in a dropped ceiling, but some of them got away."

The raiders found 20 birds already dead from the night's action, but 90 more were found in metal or wooden cages, or in the traditional pillowcase-like bags that are used to keep the cocks in the dark and relatively docile. The birds, some with values of $1,000 to $10,000, are to be destroyed humanely by the A.S.P.C.A.

"We hate to have to put down any living creature, but these birds have been trained to be so violent that we simply have no other choice," Mr. O'Neill said.

Mr. Foran said Saturday night's raid had been timed to coincide with the start of the March-to-August cockfighting season in New York, which ends with the molting season in which cocks' blood flows into quills, making them highly vulnerable and unable to fight.

He and Mr. O'Neill said that the raid had extracted a heavy toll on the cockfighting business in the metropolitan area. Since last June, the A.S.P.C.A. has seized 1,550 fighting birds -- half the estimated total in circulation -- and arrested 240 suspects. "We are waging all-out war to put ACTION DADDY out of business," Mr. O'Neill said.