After a guy scaled the bridge on Tuesday night, forcing a police response, the route across it was shut down.
Due to the incident, traffic and pedestrians were advised to take other routes.
The man is seen being filmed lying on a metal beam as spectators swarm around him.
City of London Police said: “Tower Bridge is currently closed to traffic and pedestrians due to an ongoing incident. Please find alternative routes.”
The man has been perched on the steel wires for at least an hour, and social media users have reported that the center’s main thoroughfare is experiencing traffic backups.
Additionally, police boats arrived on the site.
One witness told the Standard: “Police, ambulance, [and the] fire brigade [are] all on the middle of the bridge with officers on the pavement situated below him.”
Man climbs Tower Bridge video