One man has been shot by police near London Bridge in an incident which is being responded to "as though it is terror-related", the Metropolitan Police said.
The Metropolitan Police tweeted: "We are currently dealing with an incident at London Bridge. Please stand by for updates."
Various social media users have reported hearing gunshots from London Bridge.
READ MORE: Police called to London Bridge following reports of shots being fired
One video shows what appears to be police pulling equipment out of a vehicle nearby.
Those in the video can be heard saying: "They've actually got guns out. They've got the guns out."
BBC correspondent John McManus told BBC News that he had heard several gun shots on London Bridge.
"Just a few minutes ago I was walking across London Bridge on the south bank to the north bank of the bridge," he said.
"There appeared to be a fight going on on the other side of the bridge, with several men attacking one man."
Political commentator Owen Jones tweeted: "I'm near London Bridge, looks like a bad incident - people running, police yelling 'keep moving', lots of emergency services, area cordoned off. Stay safe everyone."