Police were warned “someone’s going to get killed” during an “abnormal” build-up of supporters outside Hillsborough’s turnstiles, a jury has been told.
Hillsborough CCTV operator Roger Houldsworth said he heard an officer giving the dire warning by radio before fans were allowed in via an exit gate.
He said opening the gate had “never, ever happened before”.
Match commander David Duckenfield denies the gross negligence manslaughter of 95 Liverpool fans.
The former South Yorkshire Police chief superintendent, of Ferndown in Dorset, was on duty during the FA Cup semi-final on 15 April 1989.
Sheffield Wednesday’s ex-club secretary Graham Mackrell, 69, denies a charge related to the stadium safety certificate and a health and safety charge.
The trial heard Mr Houldsworth was based in the club control room alongside a police officer and the club’s head of security on the day of the semi-final.
The jury was told that, at some time between 14:30 and 14:40 GMT, Mr Houldsworth could see from police and club cameras that the area outside the Leppings Lane turnstiles was “very, very crowded”.
He described the build-up of fans as “abnormal”, and said “the crush appeared to be pressing people up against the turnstiles”.
Mr Houldsworth said he could also hear a lot of “chatter” on police radio communications.
He said: “Police outside the ground were saying it was getting very dangerous and one officer said ‘if we don’t do something, someone’s going to get killed here, open the gate’.”
Mr Houldsworth said it came as a surprise to him when exit gate C was opened at 14:52.
He said: “My first thought was ‘oh my god, I hope they’ve blocked off the walkway down to the central pens’.”
The tunnel to the pens was “like a magnet to a football supporter,” because the pitch could be seen through it, said Mr Houldsworth.
He said he had witnessed officers block its entrance at a league match between Sheffield Wednesday and Manchester United.
Mr Houldsworth said he was “ashamed” that he initially believed fans spilling on to the pitch had been caused by a pitch invasion, before learning from police officers that “people were injured”.
The trial continues.