For the businesses that called the World Trade Center home, the task of accounting for thousands of workers is the next step. For some companies, it may take days, if not weeks. 

The twin towers was home to such symbols of Western economic might as the Bank of America, Kemper Insurance, Lehman Brothers, Morgan Stanley Dean Whitter, Credit Suisse First Boston and Sun Microsystems. 

Normally 50,000 people work in the twin towers, but the first attack came when many workers were not yet in their offices. Officials estimated that 10,000 to 20,000 people were in the buildings when the first plane crashed. 

Mayor Rudolph Giuliani said hospitals had treated 1,100 injured by Tuesday night. But apparently most of the victims remained buried, and ground zero was inaccessible for hours after the disaster due to the fire, smoke, wreckage and searing heat. 

The investment company Morgan Stanley had 3,500 workers in the company's individual investor businesses in the south tower. In a message posted on the company's Web site, chairman Philip Purcell said he was saddened and outraged by the attacks. 

``In spite of this tragedy, all of our businesses are functioning and will continue to function,'' he wrote. ``We are committed to resuming full operations as exchanges and markets reopen. 

Dozens of foreign companies had offices in the towers, including Sinochem American Holdings of China; Japan's Nikko Securities; Germany's CommerzBank AG; Zim-American Israeli Shipping Co. of Israel; and Cantor Fitzgerald of London. 

Detlev Rahmsdorf, a spokesman for Deutsche Bank in Frankfurt, said more than 300 people work for them in the Trade Center, in offices in the lower floors. 

Ted Meyer, another Deutsche Bank spokesman, said the company is ``working with the authorities to verify the safety of our employees.'' He said the company's financial operations were being transferred to backup facilities. 

German insurance giant Allianz had about 300 people working in the building, though they maintain they don't know which floor. 

``They were all evacuated and they're all well,'' said spokesman Hubertus Kuelps, who refused to elaborate further. 

London-based Cantor Fitzgerald International, as well as eSpeed International, which was spun off by Cantor, said they were still taking stock of the tragedy. ESpeed is an electronic trading service with more than 650 clients worldwide. Both companies had operations on the 101st and 103rd to 105th floors, and employed 1,000 workers there. 

``All of our thoughts and prayers are with our New York colleagues and their families and friends at this time,'' said Howard W. Lutnick, chairman of both companies. ``In a very difficult and confused situation we are doing all that we can to determine more about the situations of colleagues.'' 

In San Francisco, Henrik Slipsager of ABM Industries Inc., said his company employed more than 800 engineers, janitors and lighting technicians at the World Trade Center. 

``Our thoughts and prayers are with them, and with their families, co-workers and other friends. It is, of course, far too early for us to assess the human and financial toll of this tragedy,'' he said.