LONDON, Nov. 28 (CGTN) -- UK police said a man appeared to have been shot in an incident at one of the main bridges over the River Thames in central London.

"We are in the early stages of dealing with an incident at London Bridge," police said in a statement.

They added that they believed "a number of people have been injured."

Reuters news agency reported a British security source as saying a person had been stabbed in the London Bridge area.

London ambulance service said it had declared a major incident.

A BBC reporter on the bridge at the time said he saw what appeared to be a fight between a group of men, heard two shots and saw a man "prone" on the ground.

The incident happened shortly after 14:00 GMT on the north side of the bridge. People in the area were quickly ushered away from the scene, and the bridge has been closed.