When a train falls in Baltimore, it knocks out e-mail halfway around the world.

Welcome to the 21st century.

The impact of the underground train derailment was felt far and wide, from inoperable cell phones in suburban Maryland, to corporate Web pages that couldn’t be updated in Manhattan, to e-mail downed in Africa.

Fiber optic cables running through the tunnel where the train caught fire, midway on a major line between New York and Miami, were destroyed, causing headaches for several major telecommunications carriers. The fiber line had been installed in a steel pipe inside the tunnel two years ago.

A water main break above the tunnel at Howard and Lombard streets also knocked out phone service to two downtown office towers. Verizon Communications Inc. expected to have service restored Friday to 250 W. Pratt St., flooded by three feet of water, and 300 W. Pratt St., which took on 10 feet of water. Both buildings were closed Thursday, said Sandra Arnette, a phone company spokeswoman.

"This is bad," said Felix Dialoiso, vice president for LAI Construction Services Inc. in Baltimore, one of the companies summoned to reroute the fiber optic line. "This is a pretty serious situation. It carries all kinds of information."

WorldCom Inc., based in Clinton, Miss., and Metromedia Fiber Network Inc. of White Plains, N.Y., which transmit voice and data on those lines beneath Baltimore, battled service outages Thursday.

"The train derailment did affect communications traffic in the Northeast corridor," Jennifer Baker, a Worldcom spokeswoman in Washington, said at midday. "We had teams working through the night to restore communication services and the majority of our traffic is back up. We have not been allowed back in the tunnel, so we looked for alternate paths on our own network and put new cable in the area."

The fiber break also interrupted a cell phone site that served Nextel Communicatons Inc. in Montgomery County, said Audrey Schaefer, a company spokeswoman.

E-mail and e-commerce was affected in Baltimore -- and beyond.

Several blocks from the accident, the Archdiocese of Baltimore was having difficulty communicating with its 162 parishes and 10 schools because of sporadic e-mail capability.

"It just makes us realize how vulnerable we are when something that seems unrelated can affect so many things," said William Glover, technology officer for the Archdiocese. "They’ve had to reroute data traffic, so dribs and drabs of e-mails are coming in. It’s like a storm drain of data trying to push through a garden hose."

In New York City, the Hearst Corp. lost e-mail and its main links to its Web pages on the Internet, said Gary Clough, a spokesman for the media company.

The Sun’s Web site received an e- mail from an employee of the U.S. State Department at the American Embassy in Zambia, Africa, that she had been alerted from Washington that communications has been affected by the accident in Baltimore. A department spokesman in Washington said he could not confirm the report.

"Just wanted you to know that the fire in my hometown has far reaching effects ... I’m a Baltimorean, living and working in Lusaka as a Foreign Service Officer for the U.S. Dept. of State," she wrote. "We were told and have confirmed that the fire took out MCI phone wiring that runs to a point near the Washington, D.C. area that feeds our link with the State Dept. and our e-mail system."