Traffic in central London was left gridlocked after Tower Bridge became stuck open for more than an hour due to a “mechanical fault”.
Photos from the scene showed the two arms of the bridge at different angles after it failed to close, having allowed a ship to pass through along the River Thames on Saturday afternoon.
Pictures showed queues of motorists and pedestrians waiting for at least an hour from both directions.
One social media user said: “I’ve been stuck here for nearly an hour now… #TowerBridge.”
On Twitter, the Tower Bridge account said the bridge had become locked in a “raised position”.
As of 7.30pm on Saturday, the bridge had reopened to pedestrians, but drivers were still being urged by police to find other routes.
City of London Police tweeted: “BRIDGE CLOSURE. Tower Bridge is currently closed to traffic but open to pedestrians.
“Mechanics are working to fix the bridge. Please find alternative routes.”
The bridge connects the Square Mile financial district to Southwark.
In 2005 police closed the bridge for 10 hours after a technical problem meant the arms could not be lowered.