Officials also disclosed the existence of an amateur video tape showing large open spaces around the gym floor at a time when people were dying at the door. They also noted that the tragedy was so isolated in the stairwell that the basketball game was being played inside and confusion reigned on the landing above and that hardly anyone knew it was happening until it was all over.

Officials and witnesses also said that Emergency Medical Service workers did not arrive until a half-hour after the stampede and then were mobbed trying to reach the victims. Lynn Schulman, an E.M.S. spokeswoman, said the first call, at 7:17 P.M., did not suggest the seriousness of what was happening, and it was not until 7:30 P.M. that it became a high priority. She denied reports that paramedics refused to give cardio-pulmonary or mouth-to-mouth resuscitation.

Witnesses, meantime, told of a crowd of teen-agers and young people that degenerated into a mob of rowdy, tough-talking youths who cut lines and vowed to rush the doors when they opened, who arrived without tickets and pushed and shoved to get in, who diabolically kept the pressure up even after fights erupted and the screaming and panic began.

They told, too, of police officers and private security guards who did little or nothing to help, of one door open at the gym entrance where the crush was greatest, of anger flaring inside when the game was canceled because of multiple deaths at the door, and of fans rushing about in a maelstrom of chaos, stepping over the fallen, some laughing or badgering celebrities for autographs even as others were being stomped and dying.

After a meeting with other City University administrators and security officials, Dr. W. Ann Reynolds, Chancellor of the City University of New York, and Dr. Bernard W. Harleston, president of City College, held a news conference and issued a statement expressing sorrow over the deaths and other casualties, offering condolences to the victims' families and announcing a separate university investigation.

Dr. Reynolds and Dr. Harleston declined to assess blame or to say what went wrong, noting that those evaluations should await the completion of their inquiry. But they provided many new details on the event that led to the trouble and the security arrangements surrounding it. Sell-Out Was Expected

The request to hold what was billed as the first annual Heavy D and Puff Daddy Celebrity Charity Basketball Game at Nat Holman Gymnasium in Jeremiah T. Mahoney Hall was made to City College officials on Dec. 1 by Cassandra Kirnon, president of the Evening Student Government, Dr. Reynolds said. Other officials said a rap promoter identified as "Tara Geter for Sean Combs" was involved, and fliers listed KISS-FM -- radio station WRKS -- as a sponsor.