London Bridge has been closed due to a "police incident" as multiple eyewitnesses reported that pedestrians had been hit by a van.
People at the scene said that a van had ploughed onto the pavement and into people.
The bridge has been closed in both directions and passengers evacuated from the nearby London Bridge station.
Police are treating injured people and carrying them away at the end Thrale Street.
Members of the public said they were told by police to "run as fast as they could" from the scene.
There were unconfirmed reports that attackers may also have stabbed people at the scene.
Nick Archer, who was in the London Bridge area, told Sky News: "We came out (of a bar) on to the road and looked and looked to my left and there as a guy, I thought he was just drinking but he was lying on the floor.
"And then a couple of seconds later, about three police vans flew past. "He looked in a bad way."
Witnesses posted photographs of armed police on the bridge.
London Ambulance Service said multiple resources were attending the area.
Police have confirmed they are dealing with an "incident" but have given no further details as yet.
TFL said the bridge is closed in both direction due to a "serious road traffic incident".
More to follow.