Police are negotiating with a man believed to be a disgruntled lorry driver who has strapped bombs to his body and seized hostages at a training company based in Shropshire House on a busy central London street.
He has been seen throwing objects out of a fifth floor window of a building on Tottenham Court Road in central London, and police have rushed a hostage negotiator to the scene.
Tottenham Court Road has been cordoned off causing traffic chaos across the London's West End. Armed police are also at the scene.
Here are the latest pictures and video from the scene.
Policeman say the cordon will be up for hours
Abby Baafi, 27, head of training and operations at Advantage, said the man had targeted her offices and was currently holding four men hostage.