It was shortly after 2 p.m. when news and television pictures of the wholesale devastation in New York and Washington flashed around the world and saw markets plunge as the implications of the traumatic events left market operators and investors stunned.
The subsequent decision to suspend all trading on markets in the US which calls the tune for global markets added to a general sense of alarm and bewilderment in London and elsewhere.
Such was the impact of the US news that an earlier powerful rally in the FTSE 100 was wiped out within minutes and replaced by massive losses in areas, such as transport, insurance and leisure.
Even more sinister and damaging for the markets was the near panic sweeping markets as rumours of more atrocities did the rounds.
Dealers, unnerved by talk that other financial centres were likely targets of more attacks, were reluctant to discuss events and professed a preference to get out of the capital.
But the overall view was that the latest events "have to be bad for markets; it's all anti-American, anti-capitalist and shocks everyone" said one marketmaker. "It really is get out of the way time".
A senior trader in derivatives highlighted the sudden increase in the perceived risk in the market, which indicated the possibility that the FTSE 100 could fall by another 400 points, or 10 per cent, over the next four weeks; "I've never seen this scenario unfold in the past", he said.
Before the US news, London delivered an impressive performance, gradually picking up momentum and accelerating to post a session best of 5,129.0, up 95.3 in mid-morning, before easing back and up around 56 points.
Thereafter, it was mayhem with the market initially marked down and then being hit by waves of selling, mostly in specific areas, as the news grew steadily worse.
The obvious selling targets were British Airways, whose shares plummeted over 20 per cent reflecting the expected upsurge in fuel prices and plunging passenger numbers. The prospect of a sizeable decline in tourism hit the leisure and hotels sectors.
Turnover in London shot up as global investors seeking to exit markets and unable to trade in the US, used London as a proxy.
