When Tropical Storm Isabel swept through Baltimore, it left 16 feet of water in the basement of the World Trade Center, threw the lives of the 800 people who work there into chaos and destroyed the building's electrical and communications systems.

The 60 tenants of the 27-story building spent the weekend and yesterday scrambling to find places with telephones and e-mail capability where they could do business for the next month or longer.

Damage at the state-owned building at 401 E. Pratt St. has not been fully assessed but is estimated to be in the millions of dollars.

The electrical and communications systems will have to be replaced, along with 60 percent to 80 percent of the mechanical systems, said Maryland Port Administration officials who announced yesterday that the building would be closed for at least a month.

"Any time you go through something like this, you look at where you are, where you've been and where you're going," said Jack Cahalan, a spokesman for the Maryland Department of Transportation.

"As the owner of this building, we'll certainly be looking at this. We're going to look at whether there's anything that can be done to prevent a similar situation from happening again, given that it's right on the water."

Cahalan said reopening the 278,460-square-foot building would take priority for now.

"Our focus is to get that building back on line as quickly as we can for our tenants," he said. "Once that is completed, that's when you begin to look at what can be done in the future."

Among the displaced are 60 employees of the Maryland Port Administration.

Hundreds of the Trade Center's workers have taken advantage of the opportunity to return to their offices briefly to retrieve files and other materials, Richard Berkow, a spokesman for the MPA, said late yesterday.

The storm surge caused by Isabel also plunged the Candler Building, across Pratt Street at 111 Market Place, into darkness when power was cut because of flooding. The 540,000-square- foot building, which had about 6 feet of water in its basement, is expected to reopen today, said a spokesman for its owner, HRPT Properties Trust in Boston.

"With two buildings shut down, it just puts a lot of people on the street," John G. Jordan, president of Texas-based BusinesSuites, a company that leases office space, said yesterday. "You don't typically get buildings the size of these buildings that get shut down. When you think of a skyscraper, you just don't think of it flooding."

BusinesSuites has helped find space for about a dozen companies in the World Trade Center and their 150 employees.

"We've talked to law firms, shipping firms, general business firms," Jordan said. "There have been more people who've come to us than we could possibly help. People are literally waiting in line to look at space."

The outlook is brighter for those who work at the Candler Building, which is home to 14 tenants and about 1,700 employees, said David M. Lepore, senior vice president of operations for HRPT Properties Trust.

"We worked all weekend around the clock," Lepore said. "We have the building all pumped out and powered up. We're still trying to be up and running [today]. A lot of it is based on temporary power, but I think we still should be there."

This isn't the first time that the Trade Center has suffered water damage.

Few details were available yesterday, but in 1979, Tropical Storm David flooded the basement with 8 feet of water, and the telephone system had to be repaired, Berkow said. The building was closed for about a week, said Darlene K. Frank, a spokeswoman for the port.

A Sun article reported that during that storm, millions of gallons of water raced toward the Inner Harbor and met an incoming tide. Water backed up into the Inner Harbor and effectively shut down the World Trade Center. Damage totaled $1 million, ruining the building's security system, air-conditioning and elevator controls.