London's tallest building, the Shard, was evacuated on Thursday morning after smoke started billowing from the basement of the 87-story skyscraper, a fire brigade spokesman said.
The alarm was raised about 9:30 a.m. local time, and about 900 people were evacuated from the multi-purpose landmark tower. By 11:00 the fire brigade said the smoke appeared to be dissipating.
"We are investigating the source of smoke coming from the basement. There is no suggestion at this time that it is an actual fire but the building has been evacuated as a caution," the brigade spokesman said, adding that seven fire engines were at the scene.
A police spokesman said there were no reports of any injuries or arrests.
The distinctive elongated glass-clad pyramid was designed by architect Renzo Piano and has 72 habitable stories housing six companies including Qatar-based broadcaster Al Jazeera and the world's largest hospital group, Hospital Corporation of America.
New York-based investment bank Duff & Phelps, an intellectual property law firm, a venture capital group and an energy company are among the other tenants of the landmark tower that is situated near to the London Bridge train station.
Restaurants Oblix, Aqua Shard and Hutong moved into the tower last summer, and its top floors have become a tourist attraction in the capital, reserved for visitors who pay up to 30 pounds ($50) to get the highest view of London.
The Shard competes for business with other notable London skyscrapers such as the "Walkie Talkie" and the "Cheese Grater", nicknamed for the silhouettes they cast on the skyline. (Reporting by Belinda Goldsmith and Jack Stubbs, Editing by Stephen Addison)