At least 21 Japanese remained unaccounted for as of Wednesday morning after terrorist attacks rocked the United States, Japanese government officials said.

They include 17 employees of Japanese firms that had offices in the World Trade Center in New York, and a doctor whose affiliation wasn't determined as of press time.

Nomura Research Institute wasn't able to contact two of its workers attending an international conference at the trade center.

Chief Cabinet Secretary Yasuo Fukuda confirmed that Toshiya Kuge, a 20-year-old Waseda University student residing in Suginami Ward, Tokyo, was on the passenger list of a hijacked flight that crashed outside of Pittsburgh. Japanese government officials have been dispatched to the scene to confirm whether he actually boarded the plane.

Fukuda said another Japanese may have been on American Airlines Flight 11 out of Boston, one of the two planes that smashed into the World Trade Center.

The 17 company employees comprise 12 at Fuji Bank and a subsidiary, three belonging to the Chuo Mitsui Trust & Banking Co. group, and two at the former New York branch of Nishi-Nippon Bank.

According to the Foreign Ministry, 36 Japanese companies had offices in the 110-story twin skyscrapers, while 328 Japanese nationals worked there. The government has thus far been able to ascertain the whereabouts of 310 of the workers.

Fuji Bank said 113 of its 125 Japanese workers in the complex were safe. However, the whereabouts of New York branch manager Taizo Ishikawa, 50, and 11 others remain unknown. The bank had offices on the 79th to 82nd floors of one of the towers.

Chuo Mitsui Trust, on the 83rd floor, has yet to confirm whether Satoshi Kikuchihara, 43, and two of its other five Japanese employees were alive.

Nishi-Nippon Bank said its two employees were missing. They were winding up operations at the bank's former branch on the 102nd floor when the attack took place. The Fukuoka Prefecture-based regional bank closed its branch Sept. 6.

Toshio Shinya, 34, acting head of the New York branch of Shizuoka Bank, fractured his right leg and needs six weeks for recovery, but he is expected to be discharged from the hospital in the next few days.

Dai-Ichi Kangyo Bank said it has confirmed that its 80 Japanese workers were safe. The bank, however, was unable to confirm the safety of its 300 local employees.

The Industrial Bank of Japan said its 102 workers were safe, while Aioi Insurance Co. said all of its eight employees were safe.

Shizuoka Bank, a regional bank based in Shizuoka Prefecture, said its 10 employees were all alive. However, the acting branch head, 34-year-old Toshio Shinya, suffered a broken leg while fleeing the office.

Chugoku Bank, a regional bank based in Okayama Prefecture, said its seven employees were safe. San-in Godo Bank, a regional bank based in Shimane Prefecture, said its 10 Japanese employees were unharmed.

Okato Shoji Co. said its four Japanese employees based at its U.S. unit were safe.