A man has been arrested after London's Tottenham Court Road was evacuated amid reports of a bomb threat.
Police were called just before noon after computer equipment and office furniture was thrown from the fifth floor of an office building.
Witnesses claimed there were hostages; however, police said no hostages were in the building when the 48-year-old man was arrested at 15:00 BST.
Negotiators had been brought in as police attempted to arrest the man.
Witnesses reported seeing a shirtless man in "green army trousers" being led away.
The Metropolitan Police said officers were carrying out a search of Shropshire House, the building the man entered, and the surrounding area and would be there until they were sure it was safe to reopen it.
Commander Mak Chishty said police had been concerned the man may have had explosive or flammable liquids.
Ben Dunn, who works in a building opposite, told the BBC: "The people who were throwing things out of the window were shouting, 'We are being forced to do this'."
Scotland Yard said a 300m (1,000ft) cordon had been put in place.
Tottenham Court Road was evacuated while Goodge Street and Warren Street Tube stations were closed as a precaution.
'Looking for me'
Eight bus routes were also diverted.
Transport for London (TfL) urged people to avoid the area.
The Metropolitan Police said the man had a grievance against the company.
He is said to have stormed Advantage Training Services, a company which offers HGV courses.
In a video posted on YouTube by the Huffington Post UK news website, which is based in a nearby office, Abby Baafi, 27, who works at the HGV company, said: "I recognised him because he was one of our previous customers.
"He turned up, strapped up with gasoline cylinders, and threatened to blow up the office.
"He doesn't care about anything, he is going to blow up everybody.
"He was specifically looking for me but I said 'My name's not Abby' and he let me go."
'Talk of a bomb'
Joaqam Ramus, who works at nearby Cafe Fresco, said before being evacuated: "There was talk of a bomb and somebody having a hostage in a building.
"All Tottenham Court Road is closed and so are we - the police told us to shut.
"We don't know what it is but it seems someone has a hostage."
Vivien Fluskin, who works for an architectural company in the Heal's building nearby, said: "We were the last building to be evacuated and they told us to move really quickly.
"We could see riot police and mounted police.
"There are about 100 people from my building who have been moved. We've been told we probably won't be able to go back again today.
"Colleagues of mine saw a man throwing computer equipment from a building."
Tamsin Kelly, who works at the location, said two men ran into the building and said the man had a flamethrower and canisters of gas.
She added that the two men said they had been let go as they were parents and were told to leave the building.
Leon Farrell, 25, a product manager who works for AOL in Capper Street, just off Tottenham Court Road, said: "Someone ran in to our office white as a sheet and said there was someone who had taken a few people hostage but let them go as they had kids."
Publicist David Cox, who works in an adjacent building, said: "There was a guy chucking stuff out of the window - there seemed to be computers and some furniture and then papers."