By EDDIE WRENN and MATT BLAKE
Pictures from the siege at Shropshire House, Tottenham Court Road: Witnesses say hostages have been taken inside the building
Armed police have evacuated at least 1,000 workers in central London after a suspected bomber stormed an office building and took hostages.
The man, who identified himself as Michael Green, strapped gas canisters to his back before entering the office of an HGV firm on Tottenham Court Road, according to witnesses.
He is understood to have taken four hostages inside Shropshire House, amid claims he had failed a HGV training course and wanted his money back.
Officers, including explosives experts and police negotiators, sealed off the block as the man begun hurling objects including computers and filing cabinets from a fifth floor window and threatened to blow himself up.
Bystanders, some of whom reported hearing shots being fired, have now been pushed back to Euston Road, which is about half a mile from the scene.
The cordon on Tottenham Court Road, where more than 1,000 workers have been evacuated
Pictures from the siege at Shropshire House, Tottenham Court Road in London
A spokesman for Scotland Yard said: 'It is at an office building, where there is a man causing a disturbance by throwing items out of a fifth floor window.
'There are negotiators there.'
More than 1,000 people have been evacuated, it is believed. Police would not confirm reports that the man had strapped gas canisters to his body.
Abby Baafi, 27, the head of training and operations at Advantage, a company which offers HGV courses, said the man had targeted her offices and was currently holding four men hostage.
A filing cabinet is thrown from a window during the siege
She told the Huffington Post: 'We were in the office and someone came in. I recognised him because he was one of our previous customers.
'He came in with big gasoline cylinders strapped to his body and threatened to blow up the office.
'He said he doesn’t care about his life, he doesn’t care about anything, he just wants to blow up the office.
‘He was specifically looking for me but I didn’t say my name was Abby and he let me go because I am three months pregnant.'
Hostages leave the building during the siege, as the road is cleared of workers, shoppers and pedestrians
Sarah O'Meara, who works for the Huffington Post, said they evacuated their offices in nearby Capper Street after being alerted by a woman who ran into the building.
'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. It is now at Grafton Way.'
Images on the social networking site Twitter showed various items being thrown from the building, including computer monitors and piles of paper.
Ms 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 added.
Drama: Equipment was thrown out of the windows of the building
'But then the police arrived and started telling everyone: "This is serious, this is for your own safety. He has got gas".'
A police cordon was in place from Store Street to the south of the incident.
Dozens of onlookers watched and took photographs with their mobile phones.
Five marked police cars and vans could be seen lining Tottenham Court Road, as well as four ambulances.
Unmarked police vehicles also drove up to the scene and three London buses were stopped in the road with their amber lights flashing.
A police negotiator was seen speaking to the officers guarding the cordon, and he was given directions to the scene.
The siege is occurring at Shropshire House, Tottenham Court Road in London, above the Starbucks
Speaking from Tottenham Court Road, Alan Edwards, who works in the building, told SkyNews rumours were that he was aggrieved because he had been denied an HGV licence.
The man apparently stormed into the logistics office yelling: ‘I have nothing more to live for.’
Stephen Hull is executive editor of the Huffington Post UK website, which is in the same building, although unconnected to the attack, which is though to involve a logistics business.
He posted on Twitter: 'Just interviewed woman who was target of attack. Man came into logistics office strapped up with 4 canisters threatening to blow himself up.
'Abby Baafi told us she told suspect she was three months pregnant to escape.
'Abby told us she'd met suspect before. He said he didn't have anything to live for and wanted to blow the place up.'
Hostages leave the building at about 12.30pm this afternoon