Construction and office workers avoided injury when a 3-ton steel beam slipped from a crane and fell 20 feet through the 10th floor of the IBM tower downtown.

As construction workers at the tower at 100 E. Pratt St. were raising the 30-foot beam at about 10 a.m. yesterday, the beam slipped from the crane collar and crashed through the roof of a T. Rowe Price Associates Inc. office, said Bill Toohey, a spokesman for the city Department of Housing and Community Development.

"Miraculously, no one was hurt," Toohey said.

The 27-story tower is being built onto the existing 10-story building, which contains T. Rowe Price offices.

Whiting-Turner Contracting Co., the construction company, may no longer use the cranes on the job "until they use a different method for lifting the steal beam," Toohey said. The contractor has been advised to use steel collars instead of fiberglass straps for lifting, Toohey said, because, "the steel collars get a better bite into the beam."

The workers did nothing wrong, Toohey said. "But what they were doing didn't work."

Jim Ruderman, a spokesman for IBM in New York, said the 10th floor was occupied when the mishap occurred. "We'll suspend the field operations until a complete assessment is done," he said.

Ironworkers used steel cranes to remove the beam, Toohey said.

City firefighters inspecting the accident yesterday ordered that the 10th-floor electricity and water be turned off temporarily, Toohey said.

The Maryland Occupational Safety and Health program also is investigating the accident.