- NEW: A police negotiator is talking to the man at the center of the alert, London police say
- NEW: It is still unclear if it is a hostage situation, police say
- The man is throwing objects from a fifth floor window, police say
- A section of Tottenham Court Road has been closed off, police said
London (CNN) -- Police closed part of a major shopping street in central London Friday as they investigated reports of a man causing a disturbance and throwing objects from a window.
A 100-meter (330-foot) cordon has been put in place on Tottenham Court Road, London's Metropolitan Police said, and a negotiator has been sent to the scene.
The alarm was raised around noon (7 a.m. ET).
A Metropolitan Police spokesman told CNN the man at the center of the alert was still in the building.
"We are attempting to negotiate on the scene with the man," he said. "We are attempting to stop the man causing criminal damage.
"It is still unclear if it is a hostage situation."
Some people have been able to leave the building, the spokesman said.
Reports from the public suggest the man has canisters attached to him but police are not able to confirm that itself, the police spokesman said.
Officers carrying some kind of weapons -- it is not clear whether they are live firearms or taser guns -- are at the scene. Police do not commonly carry firearms in Britain.
The incident caused major disruption on a street usually busy with traffic, shoppers and local workers on their lunch break.
Goodge Street Underground station has been closed "due to a police request," Transport for London said. Warren Street Underground station, also in the area, remains open.
A number of university buildings and a major London hospital are also nearby.
CNN's Raja Razek, Nic Robertson and Claudia Rebaza contributed to this report.
