Police snipers and heavily armed officers put several blocks of central London's shopping district into lockdown Friday after a man allegedly armed with gas canisters entered an office building and threatened to blow himself up.

Police said a 48-year-old man was arrested hours after a stand off with police at Advantage, a training company near London's Tottenham Court Road that offers tests for truck drivers.

A shirtless man in green khaki pants was seen being led out with his hands behind his back by two unarmed officers. Armed officers followed behind.

British media had claimed that the man was holding people captive, but police said they were "not aware of any hostages at this stage." Police and security personnel said the incident was not terror-related and presented no risk to the upcoming 2012 summer Olympics.

Smashed office equipment — computer monitors, hard drives, files and papers — littered the sidewalk in front of 179 Tottenham Court Road, where officers continued to stand guard after the standoff ended.

An Advantage employee interviewed by The Huffington Post identified the suspect as a former customer and said he had come in "strapped up in gasoline cylinders."

"Basically he threatened to blow up the office," Abby Baafi, 27, told the news website.

Police declined to say whether he had been armed in any way.

The Huffington Post's U.K. editor Carla Buzasi told The Associated Press that her organization's offices shared a fire escape with Shropshire House, where Advantage is headquartered. She said that two people from the neighboring building rushed into her offices after the suspect arrived, sending "a ripple of panic" across the newsroom.

The website's offices were one of several buildings in the area evacuated as police with heavy weapons and riot gear got into position. Several blocks were cordoned off and subway stations were closed as office equipment was chucked from a fifth floor window.

"He threw 10 computers," 26-year-old construction worker Martynas Vristiuk said, adding that one of the computers landed on a police car.

The three-hour-long siege turned the normally bustling Tottenham Court Road into a ghost town. The motive behind the standoff wasn't immediately clear. Police Commander Mak Chishty, who gave a brief statement following the arrest, identified the suspect only as "a local man" and said the incident was over a "quite local" matter.

A phone message left with Advantage was not immediately returned.

"This was an isolated incident and has no bearing on security preparations ahead of the summer games," said a British security official on condition of anonymity because of the sensitivity of his work.

More than an hour after the arrest, sidewalks remained cordoned off as police investigated and logged evidence.

Shannon Roberts, 18, had traveled to the scene as soon as she heard on the news that an incident was under way. She said she'd seen armed officers running through the street and at one point it appeared they were carrying an individual out in their arms.

With armed police everywhere, "it looked like the London riots again," she said.


Fergus Bell, Raphael Satter and Paisley Dodds contributed to this report.