More than 50,000 people work at the World Trade Center and 150,000 visit each day, and after a terrorist attack destroyed the center’s signature twin towers, Yalies were left wondering whether their family, friends or former classmates were among those numbers.

University administrators said they don’t know how many students’ families or Yale alumni were affected in Tuesday’s devestation. All the Yale community has for now are estimates, doubts and hopes, as final news and numbers about Yale’s extended family may not reach New Haven for weeks.

“Everything right now is unclear and I am still waiting to hear from some friends who are out of touch right now,” said Alexa Courtney ’01, who was evacuated from her job at the United Nations in New York Tuesday. “Nobody’s cell phones were working … and it has been impossible to get in touch with most people.”

A large number of Yalies tried to reach their families and friends. In the Class of 2003, for example, there are about 70 students from New York City.

And then there are alumni. Of Yale’s approximately 130,000 alumni, about 12,500 Yale graduates live within 20 or 30 miles of Manhattan and about 7,500 live in the Washington, D.C., area, said Jeff Brenzel, executive director of the Yale Alumni Association.

“Of course, many of them are employed in pretty high levels and could be in those buildings,” Brenzel said.

The World Trade Center housed some of the country’s leading financial institutions — Lehman Brothers, Morgan Stanley, Bank of America, Citigroup and Credit Suisse First Boston. Some notable financial companies, such as JP Morgan and Deloitte and Touche, are not located in the Trade Center. Many financial companies are located in the World Financial Center, which is separate from the Trade Center.

But many Yalies work for companies that were based in the center. Out of the Class of 1998, for example, 170 graduates — or 13 percent of the class — went into finance and consulting, said Phil Jones, dean of Undergraduate Career Services.

“Of those you’ve got to figure that probably the majority are in New York … maybe 100,” Jones said. “In terms of overall alumni it’s very significant.”

Jones added that other industries, specifically the publishing industry, have offices in the World Trade Center. And who knows, he said, how many Yalies were visiting the Trade Center when it was attacked.

Brenzel said he has not yet heard from any alums.

“In terms of word on Yale alumni, I’m sure that we’re not going to hear for the next few days,” Brenzel said.

Neither AYA nor Undergraduate Career Services had a complete listing of which Yale alumni work at the World Trade Center or the Pentagon.

One Yale alum, retired Pentagon worker Robert Stearns GRD ’63, was at home Tuesday listening nervously to the news like everyone else. Stearns’ nephew Aaron Taylor GRD ’00 was in a building across from the World Trade Center Tuesday morning, but was confirmed safe Tuesday evening.

Stearns said he could not think of any Yale alumni who would have been in the Pentagon Tuesday morning.

Many current Yale students tried in vain to reach their friends and families with cell phones, but constantly got busy signals.

After many calls Jay Hallen ’01 was reached in Washington where he lives and works.

“It’s absolutely horrifying. My office is three blocks from the White House, and the streets were chaotic,” Hallen said. “I can’t express how stunned I am, especially when I saw the WTC fall. I almost wanted to cry.”

Hallen is a former sports editor for the News.

Former Yale College Council President Zachary Kaufman ’00 was evacuated from his Washington office Tuesday morning and went with his colleagues to a secure location.

“While I traveled through the streets of Washington, D.C., I noticed a combination of panic, disbelief, and anger I had never seen before,” Kaufman said. “One woman kept crying out that we were at war.”

The Associated Press contributed to this report.