The match commander on the day of the Hillsborough disaster has admitted he lied about fans forcing an exit gate open to enter the ground.
Relatives of the 96 fans who died gasped as David Duckenfield told the new inquests: "I apologise unreservedly to the families."
He said: "Everybody knew the truth, the fans and police knew the truth that we'd opened the gates."
Mr Duckenfield, 70, said he would regret the lie "to his dying day".
He was in charge of policing at Sheffield Wednesday's stadium on 15 April 1989 when a fatal crush developed in terraced pens allocated to Liverpool fans.
The court heard that on the day Mr Duckenfield told Graham Kelly, of the FA, that some fans had got in themselves through gate C, when the truth was that he had ordered the gate to be opened.
Christina Lambert QC, counsel for the inquests, said some witnesses have spoken of having a "clear recollection" that Mr Duckenfield "made reference to gates having been stormed".
He said he does not recall being as "dramatic" as that.
Ms Lambert asked: "Did you appreciate that what you said and indeed, what you did not say, could or might bear that meaning to Mr Kelly and others?"
He replied: "Yes ma'am. I didn't give him sufficient information to appreciate the situation as it occurred."
Mr Duckenfield went on to say: "It was a situation I was totally untrained for, totally unprecedented, and I make no excuses. I was the man who did it. But I faced a difficult situation.
"I said something rather hurriedly, without considering the position, without thinking of the consequences and the trauma, the heartache and distress that the inference would have caused to those people who were already in a deep state of shock, who were distressed. I apologise unreservedly to the families."
He told the court that he had "no idea" what motivated him to lie.
Earlier, Mr Duckenfield said it was "one of the biggest regrets of his life" that he did not consider the consequences of opening the gate.
He said he was unaware that turnstiles at the Leppings Lane end fed into an inner concourse and that gate C was opposite a tunnel into the terraces.
Mr Duckenfield said he did not think before opening the gates about blocking the tunnel off with a line of police officers - as had happened in previous years.
The inquests heard he had not been aware that at 14:30, some 5,700 fans were still trying to enter the ground outside the Leppings Lane turnstiles because he did not know the club had a system for monitoring the supporters.
It meant 800 fans would have to go through each turnstile in 30 minutes to get in for kick-off.
Mr Duckenfield said he "accepted" this was "not going to happen".
'Open the gates'
Mr Duckenfield, who had been stationed in the police control box with a bank of TV monitors, said he was "shocked" at the request from Supt Roger Marshall to open the Leppings Lane gates after police became "overwhelmed" by the number of fans.
The witness continued: "I was shocked and taken aback by it and thinking, 'Where are these people going to go if I open the gates?"'
He said another message then came through on the police radio from Mr Marshall saying: "If we don't open the gates someone's going to get killed."
Mr Duckenfield said: "That really was a shocking, terrifying moment to feel you had got to that situation."
Another officer in the police box, Mr Bernard Murray, then said to him: "Are you going to open the gates?" the jury heard.
Mr Duckenfield said: "I remember saying to him quite clearly, Mr Murray, if people are going to die I have no option but to open the gates. Open the gates."
He said he thought fans would feel "relief and comfort" in being released from the crush of the turnstiles on to the concourse.
"I think it is fair to say it is arguably one of the biggest regrets of my life that I did not foresee where the fans would go when they came in through the gates," he continued.
"I was overcome by the enormity of the situation and the decision I had to make and, as a result of that, this is probably very hard to admit, as a result of that I was so overcome probably with emotion of us having got into that situation that my mind for a moment went blank."
Mr Duckenfield was questioned in front of about 200 relatives of those who died as a result of the disaster.
Ms Lambert asked him if he "should have taken steps" to delay the start of the match.
He responded: "I accept that view now, ma'am".
Asked what he would have done had he known there were so many supporters waiting to enter, he replied: "I would have informed the club. I would have informed the referee that we had a difficulty arising and that on the evidence we had available, we should consider delaying the kick-off."
On the day of the match, police could only judge how full the pens in the terraces were by looking at CCTV and the terraces.
There were counters on the banks of turnstiles but these did not track how many people were going into each pen.
Earlier, Mr Duckenfield also told the jury he could not account for his movements for a period of more than two hours before he took up his position in the police control box on the afternoon of the semi-final.
He told the inquests his mind was "a complete blank" and he could only remember being taken "taken out" in a police car by a colleague and "we drove around".
Ms Lambert put it to Mr Duckenfield that this was a "significant period of time" and would have been a "golden opportunity" to get to know the ground better, on what was to be his first match as commander.
Mr Duckenfield agreed that it was, but said he could not recall whether it was an opportunity he had taken.
Ms Lambert also said it would have been a good opportunity for Mr Duckenfield to survey the turnstiles at the Leppings Lane end.
Again, Mr Duckenfield agreed.
He accepted it was "part of his job as a match commander to have a basic knowledge of the layout of the stadium".
Earlier the retired officer said he had urged police to ensure both sets of fans had "a good day out."
He wrote a briefing document for officers before the FA Cup semi-final between Liverpool and Nottingham Forest, the jury was told.
In the note he said: "I cannot stress too highly the word safety. The ground will be full to capacity".
He recalled telling officers that "...it was supposed to be a wonderful occasion for both the Liverpool and Notts fans. They were to come along and enjoy themselves, and we, the police service, were to ensure that they had a good day out.
"We were to be tolerant, understanding of their enthusiasm, treat them with respect, and put ourselves forward as a professional and caring organisation".
The inquests continue.
Who were the 96 victims?
BBC News: Profiles of all those who died