When the gates were opened, thousands of fans entered a narrow tunnel leading from the rear of the terrace into two overcrowded central pens (pens 3 and 4), creating pressure at the front. Hundreds of people were pressed against one another and the fencing by the weight of the crowd behind them.
As is common at domestic matches in England, opposing supporters were segregated. Nottingham Forest supporters were allocated the South Stands and Spion Kop on the east end, with a combined capacity of 29,800, reached by 60 turnstiles spaced along two sides of the ground. Liverpool supporters were allocated the North and West ends (Leppings Lane), holding 24,256 fans, reached by 23 turnstiles from a narrow concourse. Turnstiles numbered 1 to 10, 10 in all, provided access to 9,700 seats in the North Stand; a further 6 turnstiles provided access to 4,456 seats in the upper tier of the West Stand. Finally, 7 turnstiles (lettered A to G) provided access to 10,100 standing places in the lower tier of the West Stand. Although Liverpool had more supporters, Nottingham Forest was allocated the larger area, to avoid the approach routes of rival fans crossing. As a result of the stadium layout and segregation policy, turnstiles that would normally have been used to enter the North Stand from the east were off-limits and all Liverpool supporters had to converge on a single entrance at Leppings Lane. On match day, radio and television advised fans without tickets not to attend. Rather than establishing crowd safety as the priority, clubs, local authorities and the police viewed their roles and responsibilities through the 'lens of hooliganism'.
The crowd in the Leppings Lane Stand overspilled onto the pitch, where the many injured and traumatised fans who had climbed to safety congregated.
The agreed upon protocol for the South Yorkshire Metropolitan Ambulance Service (SYMAS) was that ambulances were to queue at the entrance to the gymnasium, termed the casualty reception point, or CRP.
The system of ferrying injured from any location within the stadium to the CRP required a formal declaration to be made by those in charge for it to take effect. As this declaration was not immediately performed, confusion reigned over those attempting to administer aid on the pitch. This confusion migrated to the first responders waiting in ambulances at the CRP, a location which quickly deteriorated into an ambulance parking lot. Some crews were hesitant to leave their vehicles, unsure of whether patients were coming to them, or vice versa.
A total of 42 ambulances arrived at the stadium. Out of this number, two managed of their own accord to make their way onto the pitch — while a third ambulance made its way onto the pitch at the direction of DCAO Hopkins, who felt its visibility might allay crowd concerns. The remaining 39 ambulances were collectively able to transport approximately 149 people to either Northern General Hospital, Royal Hallamshire Hospital, or Barnsley Hospital for treatment.
A total of 96 people died as a result of injuries incurred during the disaster. Ninety-four persons, aged from 10 to 67 years old, died on the day, either at the stadium, in the ambulances, or shortly after arrival at hospital. A total of 766 people were reported to have suffered injuries, although less than half required hospital treatment. The less seriously injured survivors who did not live in the Sheffield area were advised to seek treatment for their injuries at hospitals nearer to their homes.
Prime Minister Margaret Thatcher and Home Secretary Douglas Hurd visited Hillsborough the day after the disaster and met survivors.