The first inkling the 50 or 60 men in the Hongkong and Shanghai Bank in Bishopsgate had that the 26-storey building was about to be ripped apart came at about 9.45am. The bank's security guards toured the block telling everyone there might be a bomb in a lorry outside. Since bomb hoaxes are regular irritants in the City, few of the contract workers took the warning seriously. They trooped down to the underground car park and a computer room in the basement, chatting and laughing.
Steve Condon, an electrician, said: 'We were told about an hour before that there was a suspect vehicle outside. But you say to yourself 'that's not going to happen'. Down in the car park we were leaning against the cars. We thought 'Stuff this, we want to get on with our work'.'
Tony Miles, a mechanical fitter, added: 'We just sat there making jokes. And then the building shook.'
Virtually all the interior of the office above ground level was destroyed by the blast at 10.25am. Ceilings collapsed, marble was torn off the walls in reception, doors were ripped off their hinges and lifts were blown out of the shafts. Cars on the street were crushed and acres of glass windows fell into the street.
Nigel Tree, a maintenance worker, said: 'The ceiling came in, all the walls came in, whatever cars were in the car park were flattened. There's very little standing apart from the core wall.'
At the nearby NatWest Tower, security guards and workmen were on 30 different floors at the time of the explosion. Duncan Collins, 23, a pipefitter, said: 'We got a message on our bleeper that there was a bomb on the street, but we weren't evacuated.'
Windows down one side of the tower were blown out. A spokesman later described the damage as 'considerable'.
The shockwaves from the blast rippled out and hit the Moorgate tube station terrifying passengers waiting for trains. The blast was so powerful it damaged underground offices in the station 250 yards away from the bomb.
'We were in the control room when the ceiling fell in on my supervisor's head,' said David Stokes, the duty manager at the station. 'Luckily he wasn't hurt. We had no warning. But we evacuated all staff and all passengers.' Back in the Hongkong and Shanghai Bank, the workers in the car park were covered in debris and too scared to move.
'We just lay on our backs - the ceiling had come down and all the rubble was on top of us,' Mr Condon said. 'We stayed there in case there was another explosion.'
Everyone in the underground car park appeared to have escaped serious injury. But two guards patrolling the upper levels were badly hurt, the workers said. One was thrown downstairs as he emerged from searching a toilet; a second was badly cut - possibly in the building's reception area.
Les Tobbell, the bank's technical services manager, said that several others were suffering from shock and a man with heart trouble had been taken to hospital.
The workers were eventually led out of the car park to join a throng of frightened people moving from police barrier to police barrier as officers shouted warnings at them to clear the area.
Among the milling crowds was a party of 20 American teenagers on a school trip to London. They made a curious sight as, barefoot and with many wearing only boxer shorts and T-shirts, they picked their way along the glass-covered City streets. Several had plastic bags wrapped round their feet. Some were in their dressing gowns.
They had been hauled out of their beds and showers when the alarm went off in the Great Eastern Hotel, at Liverpool Street station, and were evacuated so quickly they did not have time to get dressed.
'We thought at first it was a regular hotel fire alarm,' said Jana Klien, 15, one of the party from Lexington High School, Massachusetts. The hotel staff said 'Don't worry, it's just a scare'. Then the bomb went off and we really freaked out.'
Norma Regillo, a teacher at the school and organiser of the trip, said: 'The kids were hysterical and crying. The bomb was so loud and the ground shook. But the English were very good. One girl walked by and offered to give one of our kids the stockings off her feet, can you believe it?'
'We told them they were going to have an exciting trip] This is our tenth year doing this. I love coming back. We are organising another for next year.'
After the first shock, the youngsters began to enjoy the unexpected diversion. 'We came here to see the Tower of London, Buckingham Palace, the Guards and that,' said Josh Ogden, 17, as he and his friends sat in the middle of a traffic junction near Moorgate station. 'We heard there were bombs in London but not like this]'
Many of the service workers in the HongKong and Shanghai building had been in the Baltic Exchange when it was all but destroyed. One, who did not want to be identified, said: 'I don't know how we can go on like this. We only finished repairing the damage from the last one two months ago.'
As the staff contemplated damage, guests from a wedding cancelled because of the explosion walked by. Minoru Ishihara, of Hounslow, west London, said: 'I'm very disappointed. I like the UK very much, except the IRA.'
The police casualty bureau for information on the injured is on 071 601 2800. (Photographs omitted)