The CityThe city of London was shocked and confused by the terrorist attacks, but by the end of the day executives were more concerned about the disruption to the capital's transport system than about any dislocation in the financial markets.

With Underground and bus networks closed, executives at banks and law firms were grappling with the challenge of how tens of thousands of employees were going to get home - and back again today.

Last night banks were hurriedly organising transport for employees and telling only essential staff to come into work today. Barclays, which recently moved its head office to Canary Wharf, said it would be using river services and had also hired buses to get staff to outer London train stations.

Banks and law firms based in Canary Wharf were urging employees with cars to give their colleagues a lift, while asking those with homes nearby to offer spare beds. In the City, banks were rushing to snap up hotel rooms for employees who could not find a way to get home.

Trading on the stock exchange had been under way for an hour by the time the first reports of explosions flashed across screens and most traders and bankers were already at work. As the extent became clear, banks and exchanges activated their disaster management plans, which have been refined and practised since the attacks on New York and Washington in September 2001.

However, only a handful of organisations decided to move staff to back-up locations. UBS, the Swiss bank whose offices are near Liverpool Street Station, the site of the one of the explosions, briefly evacuated its trading floor.

LCH.aClearnet, which settles stock market and commodity trades, evacuated its office near Aldgate. Other banks followed police advice and kept staff in the office, sometimes inadvertently locking visitors into the building as well.

Martin Gilbert, chief executive of Aberdeen Asset Management, the fund manager which yesterday announced it was buying Deutsche Bank's UK fund management operations, had to force his way past security guards at the German bank's offices to get to a meeting in another building.

With most people locked inside, the city was eerily quiet, with only police cars, ambulances and the occasional taxi racing through the deserted streets. Canary Wharf was also closed to all vehicles, and many staff stopped to watch news on televisions while rumours of other explosions rushed around office buildings.

Trading on the stock, bond and currency exchanges was frenzied but with no disruption to communication systems, banks and regulators said the market was continuing to operate properly.

Banks were in regular contact with each other and with the Financial Services Authority. The city regulator said it saw no "systemic effects" from the attacks.

Earlier, the centre of London had been plunged into chaos as people scrambled to get on to packed buses. Queues for phone boxes snaked down streets as mobile networks were switched off.

Amanda Mellon, a tourist from the US, said: "Maybe the world will realise terrorists don't just hate Americans. They hate you, too."