cinema to save men trapped and screaming for help.
One customer jumped onto the vehicle's roof from the first floor of the four-storey building but flames forced the van driver to move before two others could follow.
'Few people were around,' said Peter Cook, 45, from Waltham Cross, Hertfordshire, outside the gutted premises in St John Street. 'We were working in the offices next door when I first saw flames. Then the building just blew up. I ran downstairs to check my lads were safe then we backed up the van. The people inside were hysterical. My mate shouted 'jump' and one man did. There were two other men but the flames were so bad we had to back off. By then the fire brigade had arrived.
'It all happened so quickly. The place went up in five minutes. I doubt people had much chance of getting out.'
Clearly upset, Mr Cook said the middle-aged man he helped to escape had been badly shaken but did not appear to be seriously injured.
When firemen arrived within minutes of the fire being reported, the entire building was ablaze. At one point, about 20 people scrambled to get out on to a single fire brigade turntable ladder. In the panic, one man was said to have dived out of a window head first.
Valerie Martin, a local resident who was one of the first on the scene, said: 'There were people lying everywhere and they were really badly burnt - their skin, their heads, their arms. It was really horrible. The police and ambulancemen were trying to resuscitate them.'
Mrs Martin said closed circuit television cameras were installed to monitor movements up the stairs to the cinema. There were also closed- circuit cameras outside the Big Pictures photographic agency next door. 'Whoever started it, started it in the passageway. That's why people couldn't get out.'
She said she helped one of the victims who escaped from the flames. 'I held him up by his arms. He was badly burnt, the back of his neck, his arms and chest. His clothes were just stuck to his body. He couldn't move his hands, he was shaking so much.'
Mrs Martin reported seeing two men aged 18 to 22 laughing at the blaze, and gave their descriptions to police.
Yesterday the building, near Smithfield meat market, was no more than a charred shell. As investigators sifted through the debris, ragged curtains fluttered from the windowless upper floors. Just within the 50ft police cordon, the pillar of a local bank and an adjacent pavement were heavily stained with blood.
Although the area bustles on weekdays, it is quiet at weekends. Few locals appear to have known about the club. A taxi driver who has worked the area for years said he had no idea it existed. There is a rear entrance to the building, though it was not known whether it was a proper fire escape or if it was open at the time.