Aerial footage of the scene in central London, where police sent a hostage negotiator to an office block and evacuated the nearby area. Reuters

Police have arrested a 50-year-old man at the centre of an armed siege in a busy London street on Friday.

The man was seen being led away just over three hours after armed police and an explosives team were called to an office building on Tottenham Court Road.

Scotland Yard said the building was being searched but there was no indication at this time that hostages had been held.

The incident produced chaos in central London as police imposed a 300-metre cordon around the area after a witness said a man had arrived at the office of Advantage HGV with gas canisters strapped to his body and threatened to blow himself up. A police negotiator was called to the scene.

It was also reported that the man was throwing computers and other equipment out of a window.

Images on Twitter showed various items being thrown from the building, including computer monitors and piles of paper.

Ryan Murphy, an electrician who was working on the roof of 170 Tottenham Court Road, confirmed that several large items had been thrown from the building next door.

"I saw about 7 or 8 TVs or LCD screens being thrown out of the window and a couple of keyboards and filing cabinets," he said.

"I didn't know what to think. Everyone else was getting evacuated but no one had come up to see us [at that point]."

He and his workmates were eventually evacuated by an armed officer.

Reports that the man had canisters strapped to his body have not been confirmed.

In a video posted on YouTube by Stephen Hull, an editor with the Huffington Post, a witness who works at the transport and logistics firm spoke about the incident.

Abby Baafi, the head of training and operations, said she recognised him as a customer of the company, which provides HGV (heavy goods vehicle) training courses.

"He turned up, strapped up with gasoline cylinders, and threatened to blow up the office," Baafi said at the scene.

"He said he doesn't care about his life. He doesn't care about anything, he is going to blow up everybody."

She said the man had failed an HGV training course and wanted his money back.

The Metropolitan police had earlier issued a statement, saying: "Officers are in attendance at an incident in Tottenham Court Road, where a 50-year-old man is causing a disturbance.

"Police were called at 11.59am on Friday 27 April to an office building on Tottenham Court Road.

"Items, including electrical equipment, have been thrown out of a fifth-floor window."

The statement added that no injuries had been reported and it was not clear if there were other people in the building at the time.

Sarah O'Meara of the Huffington Post said the media company had evacuated its offices in nearby Capper Street after being alerted by a passerby.

"A woman ran in off the street saying: 'There is a guy with a bomb and he is threatening to blow himself up', and that we needed to evacuate," she said.

"Everyone got out. The police have been moving people back street by street."

O'Meara said the atmosphere had been "tragi-comic" until the police arrived and it turned serious.

"He was throwing stuff out of the windows – it looked like someone with a grievance," she said.

"But then the police arrived and started telling everyone: 'This is serious, this is for your own safety. He has got gas.'"

Tottenham Court Road was cordoned off from near Goodge Street tube station all the way up to the Euston Road – a distance of almost half a mile.